Mercurial > docs > unix-phil
annotate unix-phil.ms @ 3:aebbe3e76f5e
minor rework
| author | meillo@marmaro.de |
|---|---|
| date | Wed, 10 Feb 2010 13:19:04 +0100 |
| parents | fbd7baf6a61f |
| children | c707b0c5c849 |
| rev | line source |
|---|---|
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
1 .\".if n .pl 1000i |
| 0 | 2 .de XX |
| 3 .pl 1v | |
| 4 .. | |
| 5 .em XX | |
| 1 | 6 .\".nr PI 0 |
| 7 .\".if t .nr PD .5v | |
| 8 .\".if n .nr PD 1v | |
| 0 | 9 .nr lu 0 |
| 10 .de CW | |
| 11 .nr PQ \\n(.f | |
| 12 .if t .ft CW | |
| 13 .ie \\$1 .if n .ul 999 | |
| 14 .el .if n .ul 1 | |
| 15 .if t .if !\\$1 \&\\$1\f\\n(PQ\\$2 | |
| 16 .if n .if \\n(.$=1 \&\\$1 | |
| 17 .if n .if \\n(.$>1 \&\\$1\c | |
| 18 .if n .if \\n(.$>1 \&\\$2 | |
| 19 .. | |
| 20 .ds [. \ [ | |
| 21 .ds .] ] | |
| 1 | 22 .\"---------------------------------------- |
| 0 | 23 .TL |
| 24 Why the Unix Philosophy matters | |
| 25 .AU | |
| 26 markus schnalke <meillo@marmaro.de> | |
| 27 .AB | |
| 1 | 28 .ti \n(.iu |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
29 This paper discusses the importance of the Unix Philosophy in software design. |
| 0 | 30 Today, few software designers are aware of these concepts, |
| 3 | 31 and thus most modern software is limited and does not make use of software leverage. |
| 0 | 32 Knowing and following the tenets of the Unix Philosophy makes software more valuable. |
| 33 .AE | |
| 34 | |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
35 .if t .2C |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
36 |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
37 .FS |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
38 .ps -1 |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
39 This paper was prepared for the seminar ``Software Analysis'' at University Ulm. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
40 Mentor was professor Schweiggert. 2010-02-05 |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
41 .br |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
42 You may get this document from my website |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
43 .CW \s-1http://marmaro.de/docs |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
44 .FE |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
45 |
| 0 | 46 .NH 1 |
| 47 Introduction | |
| 48 .LP | |
| 49 Building a software is a process from an idea of the purpose of the software | |
| 3 | 50 to its release. |
| 0 | 51 No matter \fIhow\fP the process is run, two things are common: |
| 52 the initial idea and the release. | |
| 3 | 53 The process inbetween can be of any shape. |
| 54 The the maintainance work after the release is ignored for the moment. | |
| 1 | 55 .PP |
| 0 | 56 The process of building splits mainly in two parts: |
| 57 the planning of what and how to build, and implementing the plan by writing code. | |
| 3 | 58 This paper focuses on the planning part \(en the designing of the software. |
| 59 .PP | |
| 60 Software design is the plan of how the internals and externals of the software should look like, | |
| 61 based on the requirements. | |
| 62 This paper discusses the recommendations of the Unix Philosphy about software design. | |
| 63 .PP | |
| 64 The here discussed ideas can get applied by any development process. | |
| 65 The Unix Philosphy does recommend how the software development process should look like, | |
| 66 but this shall not be of matter here. | |
| 0 | 67 Similar, the question of how to write the code is out of focus. |
| 1 | 68 .PP |
| 3 | 69 The name ``Unix Philosophy'' was already mentioned several times, but it was not explained yet. |
| 1 | 70 The Unix Philosophy is the essence of how the Unix operating system and its toolchest was designed. |
| 3 | 71 It is no limited set of rules, but what people see to be common to typical Unix software. |
| 1 | 72 Several people stated their view on the Unix Philosophy. |
| 73 Best known are: | |
| 74 .IP \(bu | |
| 75 Doug McIlroy's summary: ``Write programs that do one thing and do it well.'' | |
| 76 .[ | |
| 77 %A M. D. McIlroy | |
| 78 %A E. N. Pinson | |
| 79 %A B. A. Taque | |
| 80 %T UNIX Time-Sharing System Forward | |
| 81 %J The Bell System Technical Journal | |
| 82 %D 1978 | |
| 83 %V 57 | |
| 84 %N 6 | |
| 85 %P 1902 | |
| 86 .] | |
| 87 .IP \(bu | |
| 88 Mike Gancarz' book ``The UNIX Philosophy''. | |
| 89 .[ | |
| 90 %A Mike Gancarz | |
| 91 %T The UNIX Philosophy | |
| 92 %D 1995 | |
| 93 %I Digital Press | |
| 94 .] | |
| 95 .IP \(bu | |
| 96 Eric S. Raymond's book ``The Art of UNIX Programming''. | |
| 97 .[ | |
| 98 %A Eric S. Raymond | |
| 99 %T The Art of UNIX Programming | |
| 100 %D 2003 | |
| 101 %I Addison-Wesley | |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
102 %O .CW \s-1http://www.faqs.org/docs/artu/ |
| 1 | 103 .] |
| 0 | 104 .LP |
| 1 | 105 These different views on the Unix Philosophy have much in common. |
| 3 | 106 Especially, the main concepts are similar for all of them. |
| 1 | 107 But there are also points on which they differ. |
| 108 This only underlines what the Unix Philosophy is: | |
| 109 A retrospective view on the main concepts of Unix software; | |
| 110 especially those that were sucessful and unique to Unix. | |
| 111 .PP | |
| 112 Before we will have a look at concrete concepts, | |
| 113 we discuss why software design is important | |
| 114 and what problems bad design introduces. | |
| 0 | 115 |
| 116 | |
| 117 .NH 1 | |
| 118 Importance of software design | |
| 119 .LP | |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
120 Why should we design software at all? |
| 3 | 121 It is general knowledge, that a bad plan is better than no plan. |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
122 As stated earlier in this document, the process of building a software |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
123 means going from an idea to a release. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
124 The development process tells how to get from the idea to the release. |
| 3 | 125 Software design is the shape of the built software. |
| 126 This means, that different designs of a software would be different target points to go to. | |
| 127 Thus, the design of a software defines the global direction the development goes. | |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
128 .PP |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
129 It is not enough that the released software offers all requested functionality. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
130 It is a misbelief that only function matters. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
131 Building a software the first time is only a small part of the overall work. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
132 The larger part begins when the software is released for the first time |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
133 \(en maintainance and extending work.. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
134 This part soon covers more time than the time which was needed to build the software the first time. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
135 .\" cf. brooks? |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
136 .PP |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
137 The extendability and maitainability of a software highly depends on its design. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
138 Good design eases these tasks much. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
139 Bad design, in contrast, requires much more effort for maintaining and |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
140 extending the software. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
141 Developers should, for their own best, have maintainability and extendability in mind |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
142 when they design the software. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
143 .PP |
| 3 | 144 Users of the software, in contrast, do not care about maintainability and extendability, |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
145 at least not directly. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
146 They care about usability and flexibility. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
147 They want the software to directly solve their problems. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
148 They want to be able to to use all its functions if they learned a few of them. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
149 They want to use the software for similar tasks. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
150 Software is successful if users enjoy using it. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
151 Good software design can offer great flexibility and usability. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
152 .PP |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
153 Good design matters for developers \fIand\fP for users. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
154 Hence both groups should care about good software design. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
155 Bad design limits the software in some way. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
156 It may still provide all requested function, but it will have worse quality, |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
157 and thus require more work effort for developers or frustrate users. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
158 .PP |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
159 Good software design is to the implementation like data structures are to algorithms |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
160 \(en if you get the former right, then you do not need to care about the latter, |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
161 it will simply go the right way. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
162 .\" cf. ??? ``good data, bad algos'' |
| 0 | 163 |
| 164 | |
| 165 | |
| 166 | |
| 167 .NH 1 | |
| 168 The Unix Philosophy | |
| 169 | |
| 170 .NH 2 | |
| 171 what it is | |
| 172 .LP | |
| 173 definitions by McIlroy, Gancarz, ESR (maybe already in the intro) | |
| 174 .LP | |
| 175 cf. unix tool chain | |
| 176 .LP | |
| 177 enabler pipe | |
| 178 | |
| 179 .NH 2 | |
|
2
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
180 Architecture |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
181 .LP |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
182 the most important design decision. |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
183 |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
184 the topic here |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
185 |
|
fbd7baf6a61f
added content about sw design; some formating
meillo@marmaro.de
parents:
1
diff
changeset
|
186 .NH 2 |
| 0 | 187 Interface architecture |
| 188 .LP | |
| 189 standalone vs. tool chain | |
| 190 .LP | |
| 191 software leverage | |
| 192 .LP | |
| 193 possiblities | |
| 194 | |
| 195 .NH 2 | |
| 196 Results | |
| 197 .LP | |
| 198 The unix phil is an answer to the sw design question | |
| 199 .LP | |
| 200 tool chains empower the uses of sw | |
| 201 | |
| 202 .NH 1 | |
| 203 Case study: nmh | |
| 204 | |
| 205 .NH 2 | |
| 206 History | |
| 207 .LP | |
| 208 MH, nmh. | |
| 209 They are old. | |
| 210 | |
| 211 .NH 2 | |
| 212 Contrasts to similar sw | |
| 213 .LP | |
| 214 vs. Thunderbird, mutt, mailx, pine | |
| 215 .LP | |
| 216 flexibility, no redundancy, use the shell | |
| 217 | |
| 218 .NH 2 | |
| 219 Gains of the design | |
| 220 .LP | |
| 221 | |
| 222 .NH 2 | |
| 223 Problems | |
| 224 .LP | |
| 225 | |
| 226 .NH 1 | |
| 227 Case study: uzbl | |
| 228 | |
| 229 .NH 2 | |
| 230 History | |
| 231 .LP | |
| 232 uzbl is young | |
| 233 | |
| 234 .NH 2 | |
| 235 Contrasts to similar sw | |
| 236 .LP | |
| 237 like with nmh | |
| 238 .LP | |
| 239 addons, plugins, modules | |
| 240 | |
| 241 .NH 2 | |
| 242 Gains of the design | |
| 243 .LP | |
| 244 | |
| 245 .NH 2 | |
| 246 Problems | |
| 247 .LP | |
| 248 broken web | |
| 249 | |
| 250 .NH 1 | |
| 251 Final thoughts | |
| 252 | |
| 253 .NH 2 | |
| 254 Quick summary | |
| 255 .LP | |
| 256 good design | |
| 257 .LP | |
| 258 unix phil | |
| 259 .LP | |
| 260 case studies | |
| 261 | |
| 262 .NH 2 | |
| 263 Why people should choose | |
| 264 .LP | |
| 265 Make the right choice! | |
| 266 | |
| 267 .nr PI .5i | |
| 268 .rm ]< | |
| 269 .de ]< | |
| 270 .LP | |
| 271 .de FP | |
| 272 .IP \\\\$1. | |
| 273 \\.. | |
| 274 .rm FS FE | |
| 275 .. | |
| 276 .SH | |
| 277 References | |
| 278 .[ | |
| 279 $LIST$ | |
| 280 .] | |
| 281 .wh -1p |