varname.mk revision 1.8 1 1.8 rillig # $NetBSD: varname.mk,v 1.8 2020/11/02 22:59:48 rillig Exp $
2 1.1 rillig #
3 1.2 rillig # Tests for special variables, such as .MAKE or .PARSEDIR.
4 1.5 rillig # And for variable names in general.
5 1.1 rillig
6 1.5 rillig .MAKEFLAGS: -dv
7 1.5 rillig
8 1.5 rillig # In variable names, braces are allowed, but they must be balanced.
9 1.5 rillig # Parentheses and braces may be mixed.
10 1.5 rillig VAR{{{}}}= 3 braces
11 1.5 rillig .if "${VAR{{{}}}}" != "3 braces"
12 1.5 rillig . error
13 1.5 rillig .endif
14 1.5 rillig
15 1.5 rillig # In variable expressions, the parser works differently. It doesn't treat
16 1.5 rillig # braces and parentheses equally, therefore the first closing brace already
17 1.5 rillig # marks the end of the variable name.
18 1.5 rillig VARNAME= VAR(((
19 1.5 rillig ${VARNAME}= 3 open parentheses
20 1.5 rillig .if "${VAR(((}}}}" != "3 open parentheses}}}"
21 1.5 rillig . error
22 1.5 rillig .endif
23 1.5 rillig
24 1.5 rillig # In the above test, the variable name is constructed indirectly. Neither
25 1.5 rillig # of the following expressions produces the intended effect.
26 1.7 rillig #
27 1.7 rillig # This is not a variable assignment since the parentheses and braces are not
28 1.7 rillig # balanced. At the end of the line, there are still 3 levels open, which
29 1.7 rillig # means the variable name is not finished.
30 1.6 rillig ${:UVAR(((}= try1
31 1.8 rillig # On the left-hand side of a variable assignments, the backslash is not parsed
32 1.8 rillig # as an escape character, therefore the parentheses still count to the nesting
33 1.8 rillig # level, which at the end of the line is still 3. Therefore this is not a
34 1.8 rillig # variable assignment as well.
35 1.6 rillig ${:UVAR\(\(\(}= try2
36 1.8 rillig # To assign to a variable with an arbitrary name, the variable name has to
37 1.8 rillig # come from an external source, not the text that is parsed in the assignment
38 1.8 rillig # itself. This is exactly the reason why further above, the indirect
39 1.8 rillig # ${VARNAME} works, while all other attempts fail.
40 1.8 rillig ${VARNAME}= try3
41 1.5 rillig
42 1.5 rillig .MAKEFLAGS: -d0
43 1.1 rillig
44 1.1 rillig all:
45