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declare function: Spaces not allowed in function's arg list #1123

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muzimuzhi opened this issue Jan 10, 2022 · 1 comment · May be fixed by #1124
Open

declare function: Spaces not allowed in function's arg list #1123

muzimuzhi opened this issue Jan 10, 2022 · 1 comment · May be fixed by #1124

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@muzimuzhi
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Brief outline of the bug

When declaring functions through key /pgf/declare function, spaces are not allowed in the arg list. For example func(\x,\y)=...; works well but func(\x,<space>\y) doesn't.

Minimal working example (MWE)

\documentclass{article}
\usepackage{pgfmath}

\pgfkeys{/pgf/declare function={
  funcA(\x,\y) = sqrt(\x^2+\y^2);
  funcB(\x, \y) = sqrt(\x^2+\y^2); 
}}

\makeatletter
% expected: #1#2->\pgfmathparse {sqrt(#1^2+#2^2)}
% actual:   #1#2->\pgfmathparse {sqrt(#1^2+\y ^2)}, note the `\y`
\show\pgfmathfuncB@
\makeatother

\begin{document}
\end{document}

Discussion

The pgfmanual examples use not a single space in such arg lists, but users are not as lucky as the manual. When declare function is used with plotting, it becomes even harder to find the cause. See TeX-SX questions https://tex.stackexchange.com/q/469153 and the ones linked to it (on TeX-SX).

This should either be documented or fixed. For a possible fix,

diff --git a/tex/generic/pgf/math/pgfmathfunctions.code.tex b/tex/generic/pgf/math/pgfmathfunctions.code.tex
index 6e5d079c..e3db1ed0 100644
--- a/tex/generic/pgf/math/pgfmathfunctions.code.tex
+++ b/tex/generic/pgf/math/pgfmathfunctions.code.tex
@@ -204,14 +204,18 @@
 
 \def\pgfmath@local@function@@body#1,{%
     \def\pgfmath@local@test{#1}%
+    % strip spaces in case #1 starts with a space, e.g., #1 is ` \y` 
+    % which comes from `func(\x, \y)=...;`
+    \expandafter\pgfkeys@spdef\expandafter\pgfmath@local@test\expandafter{\pgfmath@local@test}%
     \ifx\pgfmath@local@test\pgfutil@empty%
         \let\pgfmath@local@next=\relax%
     \else%
-        \edef\pgfmath@local@var@string{@\expandafter\pgfmath@local@gobbleone\string#1}%
+        \edef\pgfmath@local@var@string{%
+          @\expandafter\expandafter\expandafter\pgfmath@local@gobbleone\expandafter\string\pgfmath@local@test}%
         \advance\c@pgf@counta by1\relax%
         \expandafter\expandafter\expandafter\pgfmath@toks\expandafter\expandafter\expandafter=%
             \expandafter\expandafter\expandafter{\expandafter\pgfmath@char@hash\the\c@pgf@counta}%
-        \edef#1{\the\pgfmath@toks}%
+        \expandafter\edef\pgfmath@local@test{\the\pgfmath@toks}%
         \pgfmath@toks={}%
         \expandafter\pgfmath@local@function@@@body\pgfmath@local@body @%
         \edef\pgfmath@local@body{\the\pgfmath@toks}%
@hmenke
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hmenke commented Jan 10, 2022

We also have \pgfutil@trimspaces which removes all spaces around a token list (also fully expandable).

muzimuzhi added a commit to muzimuzhi/pgf that referenced this issue Jan 10, 2022
@muzimuzhi
fix(pgfmath): Strip spaces around each function arg pgf-tikz#1123
ab2aad4 
Signed-off-by: muzimuzhi <[email protected]>
muzimuzhi added a commit to muzimuzhi/pgf that referenced this issue Jan 10, 2022
@muzimuzhi
test: Add test for pgf-tikz#1123
ca7b282 
Signed-off-by: muzimuzhi <[email protected]>
muzimuzhi added a commit to muzimuzhi/pgf that referenced this issue Jan 10, 2022
@muzimuzhi
fix(pgfmath): Strip spaces around each function arg pgf-tikz#1123
7d5cc95 
Signed-off-by: muzimuzhi <[email protected]>
@muzimuzhi muzimuzhi linked a pull request Jan 10, 2022 that will close this issue
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muzimuzhi added a commit to muzimuzhi/pgf that referenced this issue Jan 10, 2022
@muzimuzhi
fix(pgfmath): Strip spaces around each function arg pgf-tikz#1123
5983e00 
Signed-off-by: muzimuzhi <[email protected]>
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declare function: Strip spaces around each function arg muzimuzhi/pgf
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@hmenke @muzimuzhi