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Comment:Correct recent makeheaders.html documentation update to respect the prohibition of multiple global variables per declaration
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SHA1: ba5ab70e96ca7e25d6c4fb3c164f221f347508cf
User & Date: andygoth 2016-11-07 04:45:23.500
Context
2016-11-07
05:43
Minor correction to example comment in Fossil coding introduction. ... (check-in: 22a9fba4 user: andybradford tags: trunk)
04:45
Correct recent makeheaders.html documentation update to respect the prohibition of multiple global variables per declaration ... (check-in: ba5ab70e user: andygoth tags: trunk)
04:06
Use disjoint timelines when filtering by the chng timeline query parameter ... (check-in: e7bdbbe4 user: andygoth tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/makeheaders.html.
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and procedure definitions.
It only understands the modern ANSI-C style, and will probably
become very confused if it encounters an old K&R function.
Therefore you should take care to avoid putting K&R function definitions
in your code.
</p>

<p>
Makeheaders does not support defining an enumerated or aggregate type in
the same statement as a variable declaration.  None of the following
statements work completely:
<pre>
struct {int field;} a;
struct Tag {int field;} b;
struct Tag c;
</pre>
Instead, define types separately from variables:
<pre>
#if INTERFACE
struct Tag {int field;};
#endif
Tag b, c;
</pre>
See <a href="#H0008">3.2 What Declarations Get Copied</a> for details,
including on the automatic typedef.
</p>

<p>
Makeheaders does not understand when you define more than one
global variable with the same type separated by a comma.
In other words, makeheaders does not understand this:
<pre>
   int a = 4, b = 5;
</pre>
The makeheaders program wants every variable to have its own
definition.  Like this:
<pre>
   int a = 4;
   int b = 5;
</pre>
Notice that this applies to global variables only, not to variables
you declare inside your functions.
Since global variables ought to be exceedingly rare, and since it is
good style to declare them separately anyhow, this restriction is
not seen as a terrible hardship.
</p>























<p>
The makeheaders program processes its source file prior to sending
those files through the C preprocessor.
Hence, if you hide important structure information in preprocessor defines,
makeheaders might not be able to successfully extract the information
it needs from variables, functions and procedure definitions.
For example, if you write this:







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and procedure definitions.
It only understands the modern ANSI-C style, and will probably
become very confused if it encounters an old K&amp;R function.
Therefore you should take care to avoid putting K&amp;R function definitions
in your code.
</p>





















<p>
Makeheaders does not understand when you define more than one
global variable with the same type separated by a comma.
In other words, makeheaders does not understand this:
<pre>
   int a = 4, b = 5;
</pre>
The makeheaders program wants every variable to have its own
definition.  Like this:
<pre>
   int a = 4;
   int b = 5;
</pre>
Notice that this applies to global variables only, not to variables
you declare inside your functions.
Since global variables ought to be exceedingly rare, and since it is
good style to declare them separately anyhow, this restriction is
not seen as a terrible hardship.
</p>

<p>
Makeheaders does not support defining an enumerated or aggregate type in
the same statement as a variable declaration.  None of the following
statements work completely:
<pre>
struct {int field;} a;
struct Tag {int field;} b;
struct Tag c;
</pre>
Instead, define types separately from variables:
<pre>
#if INTERFACE
struct Tag {int field;};
#endif
Tag a;
Tag b; /* No more than one variable per declaration. */
Tag c; /* So must put each on its own line. */
</pre>
See <a href="#H0008">3.2 What Declarations Get Copied</a> for details,
including on the automatic typedef.
</p>

<p>
The makeheaders program processes its source file prior to sending
those files through the C preprocessor.
Hence, if you hide important structure information in preprocessor defines,
makeheaders might not be able to successfully extract the information
it needs from variables, functions and procedure definitions.
For example, if you write this: