Web (programming system)

<h2 id="philosophy">Philosophy</h2>
<p>The common practice in most <a href="/facts/Programming_languages/cWTYbgWa">programming languages</a> is that the primary text is source code, optionally supplemented by descriptive text in the form of comments. Knuth proposed that making the descriptive text primary was putting things in an order more convenient for human readers, rather than the order demanded by <a href="/facts/Compiler/WNfCDFJe">compilers</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a>
</p><p>Much like TeX articles, the Web source text is divided into sections according to documentation flow.  For example, in CWEB, code sections are seamlessly intermixed in the line of argumentation.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
</p>
<h2 id="implementations">Implementations</h2>
<p>The original WEB system <a href="/facts/Dependency/ur72Dltl">depends</a> on <a href="/facts/Pascal_programming_language/b3yvp8bF">Pascal</a> and comprises two programs: 
</p>
<ul><li>TANGLE, which produces compilable Pascal code from the source texts, and</li>
<li>WEAVE, which through the use of <a href="/facts/TeX/HDrl3Yvd">TeX</a> produces nicely-formatted, printable documentation from the same source texts.</li></ul>
<p>Others:
</p>
<ul><li>CWEB (below) is a version of Web for the <a href="/facts/C_(programming_language)/Ky2No763">C programming language</a>, while</li>
<li><a href="/facts/Noweb/AAxRv8gw">noweb</a> is a separate literate programming tool, which is inspired by Web (as reflected in the name) and which is <a href="/facts/Language-independent_specification/cLfKVJcx">language agnostic</a>.</li></ul>
<p>The most significant programs written in Web are <a href="/facts/TeX/HDrl3Yvd">TeX</a> and <a href="/facts/Metafont/j7vCXw8s">Metafont</a>.  Modern TeX distributions however use another program called <a href="/facts/Web2C/AuNS5c2V">Web2C</a> to convert Web source to C.
</p>
<h2 id="cweb">CWEB</h2>

<p>CWEB is a <a href="/facts/Computer_programming/QmSsFnu0">computer programming</a> system created by <a href="/facts/Donald_Knuth/GozNzDM6">Donald Knuth</a> and Silvio Levy as a follow-up to Knuth's <i>WEB</i> <a href="/facts/Literate_programming/TvPFfD8L">literate programming</a> system, using the <a href="/facts/C_(programming_language)/Ky2No763">C programming language</a> (and to a lesser extent the <a href="/facts/C%2B%2B/Et0F2qn9">C++</a> and <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a> programming languages) instead of <a href="/facts/Pascal_(programming_language)/b3yvp8bF">Pascal</a>.
</p><p>Like WEB, it consists of two primary programs: 
</p>
<ul><li>CTANGLE, which produces compilable C code from the source texts, and</li>
<li>CWEAVE, which produces nicely-formatted printable documentation using <a href="/facts/TeX/HDrl3Yvd">TeX</a>.</li></ul>
<h3>Features</h3>
<ul><li>Can enter manual TeX code as well as automatic.</li>
<li>Makes formatting of C code suitable for <a href="/facts/Pretty_printing/GNPcN6eW">pretty printing</a>.</li>
<li>Can define sections, and can contain documentation and codes, which can then be included into other sections.</li>
<li>Writes the header code and main C code in one file, and can reuse the same sections, and then it can be tangled into multiple files for compiling.</li>
<li>Uses #line directive so that any warnings or errors refer to the .w source.</li>
<li>Include files.</li>
<li>Change files, which can be automatically merged into the code when compiling/printing.</li>
<li>Produces index of identifiers and section names in the printout.</li></ul>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Comparison_of_documentation_generators/xLydRU5z">Documentation generators</a> – While comparable with Web's WEAVE, these however generally follow the standard practice of source code first, the opposite of the Web approach.</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://www.ctan.org/pkg/web">The TeX Catalogue entry for Web</a></li>
<li><a href="https://www-cs-faculty.stanford.edu/~knuth/cweb.html">CWEB homepage</a></li>
<li><a href="https://www-cs-faculty.stanford.edu/~knuth/programs.html">Examples of programs written in Web</a>, By Donald Knuth (1981 and onward)</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Knuth, Donald E. (1992). Literate Programming. CSLI Lecture Notes. Vol. 27. Stanford, California: Center for the Study of Language and Information. <a href="/wiki/Donald_Knuth" target="_blank">/wiki/Donald_Knuth</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Silvio Levy (12 June 2004). "An example of CWEB" (PDF). Archived from the original (PDF) on 20 October 2021. <a href="https://web.archive.org/web/20211020184416/http://tex.loria.fr/litte/wc.pdf" target="_blank">https://web.archive.org/web/20211020184416/http://tex.loria.fr/litte/wc.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
</ol>

Web (programming system) open-in-new

Web (programming system)