Useless Use of...
This and That
Jan Schaumann <jschauma@netmeister.org>
99CE 1DC7 770A C5A8 09A6 0DCD 66CE 4FE9 6F6B D3D7
whoami
$ ME=$(id -un)
$ grep ${ME} /etc/passwd | cut -d: -f5
Jan Schaumann
$
whoami
$ ME=$(id -un)
$ grep ${ME} /etc/passwd | cut -d: -f5
Jan Schaumann
$ groups ${ME}
etsy netbsd sa stevens
$
In the beginning...
Subject: Search and Destroy
Date: 1995/09/06
Message-ID: <42k9bf$ja9@ixnews2.ix.netcom.com>
newsgroups: comp.unix.shell
I have a bunch of text files that contain strings containing /u. I no
longer want them to contain /u ex: /u/appl/ should be /appl/....
Should I use awk? sed? Help!
Subject: Re: Search and Destroy
Date: 1995/09/06
Message-ID: <42l1b0$sk0@flood.xnet.com>
references: <42k9bf$ja9@ixnews2.ix.netcom.com>
newsgroups: comp.unix.shell
> I have a bunch of text files that contain strings containing /u. I no
> longer want them to contain /u ex: /u/appl/ should be /appl/....
>
> Should I use awk? sed? Help!
cat file | sed -e "s!/u/!/!"
Enter Merlyn
Headshot of Randal Schwartz by Chris Marquardt
Subject: This week's Useless Use of Cat Award goes to... (was Re: Search and Destroy)
Date: 1995/09/06
Message-ID: <ukspm9r5lf.fsf_-_@linda.teleport.com>
newsgroups: comp.unix.shell
|
This week's Useless Use of Cat Award goes to...
"Hemant" == Hemant Shah <s...@flood.xnet.com> who writes:
Hemant> cat file | sed -e "s!/u/!/!"
which, using the simple rule that:
cat fred | barney junk junk junk ...
can nearly always be rewritten as:
<fred barney junk junk junk ...
would look like this:
<file sed -e "s!/u/!/!"
|
|
Subject: This week's Useless Use of Cat Award goes to... (was Re: Search and Destroy)
Date: 1995/09/06
Message-ID: <ukspm9r5lf.fsf_-_@linda.teleport.com>
newsgroups: comp.unix.shell
|
This week's Useless Use of Cat Award goes to...
"Hemant" == Hemant Shah <s...@flood.xnet.com> who writes:
Hemant> cat file | sed -e "s!/u/!/!"
which, using the simple rule that:
cat fred | barney junk junk junk ...
can nearly always be rewritten as:
<fred barney junk junk junk ...
would look like this:
<file sed -e "s!/u/!/!"
|
|
Useful Use of Cat?
The obvious examples first:
cat file | grep pattern
cat file | awk '{ print $2; }' |
|
Useless Use of Cat!
The obvious examples first:
cat file | grep pattern
grep pattern <file
cat file | awk '{ print $2; }'
awk '{ print $2; }' <file |
|
Useless Use of Cat!
The obvious examples first:
cat file | grep pattern
grep pattern <file
cat file | awk '{ print $2; }'
awk '{ print $2; }' <file
I would also accept:
grep pattern file
awk '{ print $2; }' file
|
|
Useless Use of Cat!
The obvious examples first:
cat file | grep pattern
grep pattern <file
cat file | awk '{ print $2; }'
awk '{ print $2; }' <file
I would also accept:
grep pattern file
awk '{ print $2; }' file
Or:
<file grep pattern
<file awk '{ print $2; }'
|
|
Useful Use of Cat?
cat file1 file2 file3 | wc -l
cat file1 file2 file3 | wc -w
|
|
Useless Use of Cat!
cat file1 file2 file3 | wc -l
awk 'END { print NR }' file1 file2 file3
cat file1 file2 file3 | wc -w
awk '{w = w + NF} END { print w }' file1 file2 file3
|
|
Useless Use of Cat! - TMTOWTDI
cat file1 file2 file3 | wc -l
awk 'END { print NR }' file1 file2 file3
sed -n -e '$=' file1 file2 file3
cat file1 file2 file3 | wc -w
awk '{w = w + NF} END { print w }' file1 file2 file3
...left as an exercise...
|
|
Even More Useless Use of Cat
cat file1 file2 file3 | grep pattern
if [ $(cat files | grep -c pattern) -gt 0 ]; then
|
|
Even More Useless Use of Cat
cat file1 file2 file3 | grep pattern
grep -h pattern file1 file2 file3
if [ $(cat files | grep -c pattern) -gt 0 ]; then
if [ -n "$(grep -l pattern files)" ]; then
|
|
Even More Useless Use of Cat - TMTOWTDI
cat file1 file2 file3 | grep pattern
grep -h pattern file1 file2 file3
awk '/pattern/ { print }' file1 file2 file3
if [ $(cat files | grep -c pattern) -gt 0 ]; then
if [ -n "$(grep -l pattern files)" ]; then
if grep pattern files >/dev/null 2>&1; then
|
|
Useful Use of Cat
-
concatenate and print files
cat * > file
Useful Use of Cat
Cat5 (now actually less useful)
|
Cat6
|
Why bother?
Why bother?
Why bother?
Why bother?
So.... cats are stupid. What else?
Useless Use of Grep
Of course, all use of grep(1) is useless!
echo g/RE/p | ed -s file
Useful Use of Grep?
host hostname | grep 'has address' | awk '{ print $NF }'
echo ${string} | grep 'pattern' | sed -e 's/foo/bar/'
|
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Useless Use of Grep!
host hostname | grep 'has address' | awk '{ print $NF }'
host hostname | awk '/has address/ { print $NF}'
echo ${string} | grep 'pattern' | sed -e 's/foo/bar/'
echo ${string} | sed -n -e '/pattern/ s/foo/bar/p'
|
|
Useful Use of Grep?
grep pattern1 file | grep -v pattern2
grep pattern1 file | grep -v ^# | grep -v pattern2
|
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Useless Use of Grep!
grep pattern1 file ... | grep -v pattern2
awk '/pattern1/ && !/pattern2/ { print }' file
grep pattern1 file | grep -v ^# | grep -v pattern2
awk '/pattern1/ && !/(^#)|(pattern2)/ { print }
|
|
Useless Use of Grep!
grep pattern1 file ... | grep -v pattern2
awk '/pattern1/ && !/pattern2/ { print }' file
grep pattern1 file | grep -v ^# | grep -v pattern2
awk '/pattern1/ && !/(^#)|(pattern2)/ { print }
ps waux | grep cmd | grep -v grep
|
|
Useless Use of Grep!
grep pattern1 file ... | grep -v pattern2
awk '/pattern1/ && !/pattern2/ { print }' file
grep pattern1 file | grep -v ^# | grep -v pattern2
awk '/pattern1/ && !/(^#)|(pattern2)/ { print }
ps waux | grep cmd | grep -v grep
ps waux | grep [c]md
|
|
Useful Use of Grep!
Useful Use of Sed?
for p in $(echo ${PATH} | sed -e 's/:/ /'); do
ls ${p}
done
|
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Useless Use of Sed!
for p in $(echo ${PATH} | sed -e 's/:/ /'); do
IFS=":"; for p in ${PATH}; do
ls ${p}
done
|
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ls /usr/share/ikea
ls /usr/share/ikea
ls /usr/share/ikea
ls /usr/share/ikea
ls /usr/share/ikea
Useful Use of Sed!
s/[0-9]/<&/g
s/0//g; s/1/|/g; s/2/||/g; s/3/|||/g; s/4/||||/g; s/5/|||||/g;
s/6/||||||/g
s/7/|||||||/g; s/8/||||||||/g; s/9/|||||||||/g
: tens
s/|</<||||||||||/g
t tens
s/<//g
s/+//g
: minus
s/|-|/-/g
t minus
s/-$//
: back
s/||||||||||/</g
s/<\([0-9]*\)$/<0\1/
s/|||||||||/9/; s/||||||||/8/; s/|||||||/7/; s/||||||/6/; s/|||||/5/;
s/||||/4/
s/|||/3/; s/||/2/; s/|/1/
s/</|/g
t back
http://is.gd/m62ijc
Useful Use of Sed?
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
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Useful Use of Sed?
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
VAR_A=${VAR%%-*}
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Useful Use of Sed?
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
VAR_A=${VAR%%-*}
VAR_C=${VAR##*-}
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Useful Use of Sed?
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
VAR_A=${VAR%%-*}
VAR_B=${${VAR%-*}#*-} # Wait, does this work?
VAR_C=${VAR##*-}
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Useful Use of Sed?
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
VAR_A=${VAR%%-*}
VAR_B=${${VAR%-*}#*-}
sh: Syntax error: Bad substitution
VAR_C=${VAR##*-}
|
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Useless Use of Sed!
VAR="foo-bar-baz"
VAR_A=$(echo ${VAR} | sed -e 's/-.*//')
VAR_B=$(echo ${VAR} | sed -e 's/[^-]*-\([^-]*\)-.*/\1/')
VAR_C=$(echo ${VAR} | sed -e 's/.*-//')
IFS=-
set -- ${VAR}
VAR_A="${1}"
VAR_B="${2}"
VAR_C="${3}"
|
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IFS is teh Rox0r!!1!
Look, Ma: reading a CSV with shell Only!
$ IFS=","
$ while read -r field1 waste field3 field4 waste; do
echo "${field1}: ${field4} --> ${field3}"
done <file
$
Useless Use of IFS!
$ cat >script.sh
IFS=","
while read -r field1 waste field3 field4 waste; do
echo "${field1}: ${field4} --> ${field3}"
done <file
^D
$ wc -l file
111061 file
$ time sh script.sh >/dev/null
12.33s real 3.30s user 8.54s system
$
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Useful Use of AWK
$ cat >script2.sh
awk -F"," '{ print $1 ": " $4 " --> " $3 }' <file
^D
$ time sh script2.sh >/dev/null
1.08s real 1.08s user 0.00s system
$
Useful Use of ls?
for file in $(ls *pattern*); do
the_needful
done
|
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Useless Use of ls!
for file in $(ls *pattern*); do
for file in *pattern*; do
the_needful
done
|
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Useful Use of wc?
| VAR="$(cat file | wc -l | sed -e 's/ *//g')"
|
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Useful Use of wc?
VAR="$(cat file | wc -l | sed -e 's/ *//g')"
VAR="$(wc -l <file | sed -e 's/ *//g')"
|
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Useless Use of wc and sed!
VAR="$(cat file | wc -l | sed -e 's/ *//g')"
VAR="$(wc -l <file | sed -e 's/ *//g')"
VAR="$(awk 'END { print NR }' file)"
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Useful Use of wc!
VAR="$(cat file | wc -l | sed -e 's/ *//g')"
VAR="$(wc -l <file | sed -e 's/ *//g')"
VAR="$(awk 'END { print NR }' file)"
VAR="$(wc -l <file)"
echo "${VAR}"
echo ${VAR}
|
|
Useful Use of head?
command1 | head -1 | sed -e 's/pattern/string/'
command1 | head -10 | sed -e 's/pattern/string/'
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Useless Use of head!
command1 | head -1 | sed -e 's/pattern/string/'
command1 | sed -e 's/pattern/string/;q'
command1 | head -10 | sed -e 's/pattern/string/'
command1 | sed -e 's/pattern/string/;10q'
|
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Useful Use of tail?
command1 | tail -1 | sed -e 's/pattern/string/'
command1 | tail -10 | sed -e 's/pattern/string/'
|
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Useless Use of tail!
command1 | tail -1 | sed -e 's/pattern/string/'
command1 | sed -n -e '$s/pattern/string/p'
command1 | tail -10 | sed -e 's/pattern/string/'
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Useful Use of tail!
command1 | tail -1 | sed -e 's/pattern/string/'
command1 | sed -n -e '$s/pattern/string/p'
command1 | tail -10 | sed -e 's/pattern/string/'
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Count HTTP status codes
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
sed -e 's/.*GET.*HTTP[^ ]*" \([^ ]*\).*/\1/' | \
grep ^2 | wc -l
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Count HTTP status codes
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
sed -e 's/.*GET.*HTTP[^ ]*" \([^ ]*\).*/\1/' | \
grep ^2 | wc -l
sed -e 's/.*GET.*HTTP[^ ]*" \([^ ]*\).*/\1/' | grep -c ^2
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Count HTTP status codes
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
sed -e 's/.*GET.*HTTP[^ ]*" \([^ ]*\).*/\1/' | \
grep ^2 | wc -l
sed -e 's/.*GET.*HTTP[^ ]*" \([^ ]*\).*/\1/' | grep -c ^2
awk '/HTTP\/[^ ]*" 200 / { c++; } END { print c }'
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MEASURE ALL THE THINGS!
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
$ time sed -n -e '/HTTP\/[^ ]*" 2/p' | wc -l >/dev/null # TMTOWTDI
real 4m16.154s
user 4m13.461s
sys 0m3.955s
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MEASURE ALL THE THINGS!
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
$ time sed -n -e '/HTTP\/[^ ]*" 2/p' | wc -l >/dev/null # TMTOWTDI
real 4m16.154s
user 4m13.461s
sys 0m3.955s
$ time awk '/HTTP\/[^ ]*" 2/ { c++; } END { print c }' >/dev/null
real 1m3.647s
user 0m57.873s
sys 0m2.234s
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MEASURE ALL THE THINGS!
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
$ time perl -lne 'if (m/HTTP\/[^ ]*" 2/) { $n++; } END { print $n; }'
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Wut? Perl? Surely you jest!
$ ldd `which awk` `which sed` `which perl`
/usr/bin/awk:
-lc.12 => /usr/lib/libc.so.12
-lm.0 => /usr/lib/libm.so.0
/usr/bin/sed:
-lc.12 => /usr/lib/libc.so.12
/usr/pkg/bin/perl:
-lc.12 => /usr/lib/libc.so.12
-lm.0 => /usr/lib/libm.so.0
-lcrypt.0 => /usr/lib/libcrypt.so.0
-lpthread.0 => /usr/lib/libpthread.so.0
-lperl => /usr/pkg/lib/perl5/5.14.0/x86_64-netbsd-thread-multi/CORE/libperl.so
$ du -h /usr/bin/awk /usr/bin/sed /usr/pkg/bin/perl \
/usr/pkg/lib/perl5/5.14.0/x86_64-netbsd-thread-multi/CORE/libperl.so
154K /usr/bin/awk
34K /usr/bin/sed
12K /usr/pkg/bin/perl
1.5M /usr/pkg/lib/perl5/5.14.0/x86_64-netbsd-thread-multi/CORE/libperl.so
MEASURE ALL THE THINGS!
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
$ time perl -lne 'if (m/HTTP\/[^ ]*" 2/) { $n++; } END { print $n; }'
real 0m22.146s
user 0m15.827s
sys 0m1.662s
Useful Use of Perl!
207.38.139.33 - - [18/Apr/2012:18:41:11 -0400] "GET /slides/nycbug201205/pics/grep-eyes.png HTTP/1.1" 200 191432 "http://www.netmeister.org/slides/nycbug201205/" "Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_4_11; en) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/4.1.3 Safari/533.19.4"
$ time perl -lne 'if (m/HTTP\/[^ ]*" 2/) { $n++; } END { print $n; }'
real 0m22.146s
user 0m15.827s
sys 0m1.662s
92% performance increase compared to sed
65% performance increase compared to awk
The Prime Directive
Worse is Better
- Simplicity -- most important
- Correctness -- slightly better to be
simple than correct
- Consistency -- better to drop less
common use cases than to introduce
complexity or inconsistency
- Completeness -- completeness can be
sacrificed in favor of any other quality
|
http://is.gd/4DRphb
|
Remember how a web server used to work?
Remember how a web server used to work?
Client: "Hello, I'd like to get the contents of this file, please."
GET / HTTP/1.0\n\n
Remember how a web server used to work?
Client: "Hello, I'd like to get the contents of this file, please."
GET / HTTP/1.0\n\n
Server: "Why, certainly, here you go."
cat file > socket
Remember how a web server used to work?
Client: "Hello, I'd like to get the contents of this file, please."
GET / HTTP/1.0\n\n
Server: "Why, certainly, here you go."
cat file > socket
HTTP today...
Client: "Hello, I'd like to get the contents of this file on this server, please."
GET / HTTP/1.1\n
Host: this server\n\n
HTTP today...
Client: "Hello, I'd like to get the contents of this file on this server, please."
GET / HTTP/1.1\n
Host: this server\n\n
Server: "I'm sorry, Node.js just crashed."
HTTP/1.1 500 Internal Server Error
Server: Apache-Coyote/1.1
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
Server: "Oh, sure, I'm a Tomcat server!"
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
Server: "Oh, sure, I'm a Tomcat server!"
Client: "So I'm talking to... your Coyote 'HTTP connector', which hands my requests off to your Catalina servlet container, which..."
Server: "...looks up stuff in various databases, triggers actions in a message broker and hands the LESS compilation off to Node.js..."
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
Server: "Oh, sure, I'm a Tomcat server!"
Client: "So I'm talking to... your Coyote 'HTTP connector', which hands my requests off to your Catalina servlet container, which..."
Server: "...looks up stuff in various databases, triggers actions in a message broker and hands the LESS compilation off to Node.js..."
Client: "Uhm... LESS? 'Compilation'? Why don't you just serve the plain old CSS?"
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
Server: "Oh, sure, I'm a Tomcat server!"
Client: "So I'm talking to... your Coyote 'HTTP connector', which hands my requests off to your Catalina servlet container, which..."
Server: "...looks up stuff in various databases, triggers actions in a message broker and hands the LESS compilation off to Node.js..."
Client: "Uhm... LESS? 'Compilation'? Why don't you just serve the plain old CSS?"
Server: "Don't be silly. 'All problems in computer science can be solved by another level of indirection.' Now where was I?"
HTTP today...
Client: "Uhm... Node.js? I thought you said you're an Apache server?"
Server: "Oh, sure, but I hand off LESS compilation to Node.js, which is faster than Rhino."
Client: "Uhm... rhino? So you're running Javascript inside Java?"
Server: "Oh, sure, I'm a Tomcat server!"
Client: "So I'm talking to... your Coyote 'HTTP connector', which hands my requests off to your Catalina servlet container, which..."
Server: "...looks up stuff in various databases, triggers actions in a message broker and hands the LESS compilation off to Node.js..."
Client: "Uhm... LESS? 'Compilation'? Why don't you just serve the plain old CSS?"
Server: "Don't be silly. 'All problems in computer science can be solved by another level of indirection.' Now where was I?"
Server: "Oh, right: ...hands the LESS compilation off to Node.js, which just crashed."
HTTP today...
Client: "My head hurts. How did I get here?"
So... what about those layers?
All problems in computer science can be solved by another level of indirection.
David Wheeler
Layers are bad...
...when all they do is provide indirection, obfuscation and increase complexity.
$ echo moo > 1
$ for i in `jot 100`; do
> ln -s $i $(($i + 1))
done
$ cat 100
cat: 100: Too many levels of symbolic links
$
Layers are good...
...when they provide security.
Layers are good...
...when they provide abstraction.
Layers are good...
...when they make things taste better.
Complexity is the Enemy
- essential complexity: inherent to the
problem; cannot be reduced
An HTTP server has to, at some point,
shuffle data from somewhere to the client.
Complexity is the Enemy
- essential complexity: inherent to the
problem; cannot be reduced
An HTTP server has to, at some point,
shuffle data from somewhere to the client.
- accidental complexity: inadvertently
and often indirectly introduced
The data can be static. Making it dynamic
adds complexity.
Complexity is the Enemy
- essential complexity: inherent to the
problem; cannot be reduced
An HTTP server has to, at some point,
shuffle data from somewhere to the client.
- accidental complexity: inadvertently
and often indirectly introduced
The data can be static. Making it dynamic
adds complexity.
Software complexity increases non-linearly, frequently exponentially!
Complexity is the Enemy
- essential complexity: inherent to the
problem; cannot be reduced
An HTTP server has to, at some point,
shuffle data from somewhere to the client.
- accidental complexity: inadvertently
and often indirectly introduced
The data can be static. Making it dynamic
adds complexity.
Software complexity increases non-linearly, frequently exponentially!
Wait... the same could be said about:
Useless Use of Message Queues
SysV and "message-oriented middleware" (insert your MOM joke here)
Wait... the same could be said about:
Useless Use of Message Queues
SysV and "message-oriented middleware" (insert your MOM joke here)
Useless Use of Complex Formats
XML makes me YAML.
Wait... the same could be said about:
Useless Use of Message Queues
SysV and "message-oriented middleware" (insert your MOM joke here)
Useless Use of Complex Formats
XML makes me YAML
Useless Use of DSL
Greenspun's 10th Rule of Programming
Any sufficiently complicated C or Fortran program
contains an ad hoc, informally-specified, bug-ridden, slow implementation
of half of Common Lisp.
Philip Greenspun
Wait... the same could be said about:
Useless Use of Message Queues
SysV and "message-oriented middleware" (insert your MOM joke here)
Useless Use of Complex Formats
XML makes me YAML
Useless Use of DSL
Greenspun's 10th Rule of Programming
Useless Use of NoSQL, Cassandra, Hadoop, ...
Old and busted vs. new hotness ("Oooh, shiny!")
Wait... the same could be said about:
...all sorts of things.
Wait... the same could be said about:
...all sorts of things.
Precisely.
Worse is Better
Simplicity
The design must be simple, both in implementation and
interface. It is more important for the implementation to
be simple than the interface. Simplicity is the most
important consideration in a design.
Worse is Better
Simplicity
The design must be simple, both in implementation and
interface. It is more important for the implementation to
be simple than the interface. Simplicity is the most
important consideration in a design.
...but...
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