Hi,
I recently came across what I believe is a bug in rake, however, I
could be wrong. Here is the behavior in question. When I right a rule
with two prerequisites everything works fine if both prerequisites
exists. The problem occurs when the second or both prerequisites do
not exist. In this case the first prerequisite task is invoked twice
and the second task not at all. For example, the following Rakefile
demonstrates the described behavior
============================ Rakefile ============================
rule '.avi' => ['.wmv'] do |t|
sh %{touch #{t.name}}
end
rule '.aac' => ['.avi'] do |t|
sh %{touch #{t.name}}
end
rule '.h264' => ['.avi'] do |t|
sh %{touch #{t.name}}
end
rule '.mp4' => ['.aac', '.h264'] do |t|
sh %{touch #{t.name}}
end
=========================== End Rakefile ==========================
The output for the command 'test.mp4' given that test.wmv exits is:
============================= Output =============================
(in /Users/aknight/rake)
touch test.avi
touch test.aac
touch test.aac
touch test.mp4
============================ End Output ==========================
The output illustrates the improper behavior. Rather than touching
'test.h264', Rake touches test.aac twice. First, the test.aac task
should not be invoked twice, and second, the test.h264 task is never
invoked.
Is this the desired behavior for Rake? I've tried a similar setup in
Make and it seems to work as I would expect and invokes tasks for
both the .aac and .h264 file. My argument is not that Rake should
work like Make, but I just wanted to see if my thinking was
completely stupid or not.
I've found where the bug is (if it acutally is a bug), created a
patch and tested it. The patch seems to make Rake work in the desired
way. If you also agree that Rake should be have in this way, let me
know and I'll submit the patch. It's a quick fix. I've tested the
patch with different combinations of files existing and it seems to
work. Also, I've tested it with more than two prerequisites and the
unpatched behavior is similar, and the patch also creates the desired
behavior in this case.
Thanks
Allan Knight
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