Différences

Ci-dessous, les différences entre deux révisions de la page.

--- 2_composition:macros:definir_une_macro_a_l_interieur_d_une_autre_macro [2018/05/24 19:11]
joseph.wright
+++ 2_composition:macros:definir_une_macro_a_l_interieur_d_une_autre_macro [2018/12/04 00:25] (Version actuelle)
jejust
@@ Ligne 1: / Ligne 1: @@
----
+====== Defining macros within macros ======
-section: Macro programming
-subsection: ''Generic'' macros and techniques
-permalink: /FAQ-hash.html
-date: 2014-06-10
----
-# Defining macros within macros
-The way to think of this is that `##` gets replaced by `#` in just the
+The way to think of this is that ''##'' gets replaced by ''#'' in just the
-same way that `#1` gets replaced by ''whatever is the first argument''.
+same way that ''#1'' gets replaced by "whatever is the first argument".
 So if you define a macro:
-```latex
+<code latex>
 \newcommand\a[1]{+#1+#1+#1+}
-```
+</code>
-or (using the TeX primitive `\def`):
+or (using the TeX primitive ''\def''):
-```latex
+<code latex>
 \def\a#1{+#1+#1+#1+}
-```
+</code>
-and use it as `\a{b}`,
+and use it as ''\a{b}'',
-the macro expansion produces ''+b+b+b+'',
+the macro expansion produces "+b+b+b+",
 as most people would expect.
 However, if we now replace part of the macro:
-```latex
+<code latex>
 \newcommand\a[1]{+#1+\newcommand\x[1]{xxx#1}}
-```
+</code>
-then `\a{b}` will give us the rather odd
+then ''\a{b}'' will give us the rather odd
-  +b+`\newcommand{x}[1]{xxxb}`
+  +b+''\newcommand{x}[1]{xxxb}''
-so that the new `\x` ignores its argument.
+so that the new ''\x'' ignores its argument.
 If we use the TeX primitive:
-```latex
+<code latex>
 \def\a#1{+#1+\def\x #1{xxx#1}}
-```
+</code>
-`\a{b}` will expand to ''+b+<code class="verb">&#x5c;def&#x5c;x b&#7b;xxxb&#x7d;</code>''.  This
+''\a{b}'' will expand to "+b+''\def\x b{xxxb}''".  This
-defines `\x` to be a macro _delimited_ by `b`, and taking no
+defines ''\x'' to be a macro //delimited// by ''b'', and taking no
 arguments, which is surely not what was intended!
-Actually, to define `\x` to take an argument, we need
+Actually, to define ''\x'' to take an argument, we need
-```latex
+<code latex>
 \newcommand\a[1]{+#1+\newcommand\x[1]{xxx##1}}
-```
+</code>
 or, using the TeX primitive definition:
-```latex
+<code latex>
 \def\a#1{+#1+\def\x ##1{xxx##1}}
-```
+</code>
-and `\a{b}` will expand to
+and ''\a{b}'' will expand to
-  +b+<code class="verb">&#x5c;def&#x5c;x #1{xxx#1&#x7d;</code>
+  +b+''\def\x #1{xxx#1}''
-because `#1` gets replaced by ''b''
+because ''#1'' gets replaced by "b"
-and `##` gets replaced by `#`.
+and ''##'' gets replaced by ''#''.
 To nest a definition inside a definition inside a definition then you
-need `####1`, doubling the number of `#` signs; and at the next level
+need ''####1'', doubling the number of ''#'' signs; and at the next level
-you need 8&nbsp;`#`s each time, and so on.
+you need 8 ''#''s each time, and so on.
+-----
+//Source:// [[faquk>FAQ-hash|Defining macros within macros]]
+{{htmlmetatags>metatag-keywords=(LaTeX,programming)
+metatag-og:title=(Defining macros within macros)
+metatag-og:site_name=(FAQ LaTeX francophone)
+}}