AutoGen: 3.3.2 Basic Expression

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### 3.3.2 Basic Expression

A basic expression can have one of the following forms:

``'STRING''`

  A single quoted string. Backslashes can be used to protect single quotes (`'`), hash characters (`#`), or backslashes (`\`) in the string. All other characters of STRING are output as-is when the single quoted string is evaluated. Backslashes are processed before the hash character for consistency with the definition syntax. It is needed there to avoid preprocessing conflicts.

``"STRING"'`

  A double quoted string. This is a cooked text string as in C, except that they are not concatenated with adjacent strings. Evaluating "`STRING`" will output STRING with all backslash sequences interpreted.

```STRING`'`

  A back quoted string. When this expression is evaluated, STRING is first interpreted as a cooked string (as in `"STRING"') and evaluated as a shell expression by the AutoGen server shell. This expression is replaced by the stdout output of the shell.

``(STRING)'`

  A parenthesized expression. It will be passed to the Guile interpreter for evaluation and replaced by the resulting value.

  Additionally, other than in the `%` and `?%` expressions, the Guile expressions may be introduced with the Guile comment character (`;`) and you may put a series of Guile expressions within a single macro. They will be implicitly evaluated as if they were arguments to the `(begin ...)` expression. The result will be the the result of the last Guile expression evaluated.

This document was generated by Bruce Korb on July, 28 2005 using texi2html 1.76.