doc: correct the build instructions for the example #202

1. 
   Eunovo commented at 7:50 am on September 3, 2025: contributor

   The make target to build the example executable is “mpexample”, not “example”, so make example does nothing. This PR changes the documentation to use “mpexamples”, because that builds the calculator, printer and example executables.
2. 
   DrahtBot commented at 7:50 am on September 3, 2025: none

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3. doc: correct the build instructions for example

   The make target to build the example executable is "mpexample" not "example".
   This commit uses "mpexamples" in the doc, because that builds
   the calculator, printer and example executables.

   b6d3dc4419
4. Eunovo force-pushed on Sep 3, 2025
5. Eunovo renamed this:
   doc: correct the build instructions for example
   doc: correct the build instructions for the example
   on Sep 3, 2025
6. in doc/usage.md:26 in b6d3dc4419

   23-build/example/mpexample
   24+mkdir build
   25+cd build
   26+cmake ..
   27+make mpexamples
   28+example/mpexample
   

   ---

   ---

   

   ismaelsadeeq commented at 7:55 am on September 3, 2025:

   I think we prefer

   0cmake -B build
   1make -C build mpexample
   2build/example/mpexample
   

   ---

   

   Eunovo commented at 7:59 am on September 3, 2025:

   I tried the cmake -B build approach as well, but this generates the warning kj/filesystem-disk-unix.c++:1740: warning: PWD environment variable doesn't match current directory; pwd = <PATH_To_LOCAL_REPO>/libmultiprocess . This warning occurs because there’s a mismatch between:

   • The PWD environment variable and
   • The actual current directory.

   It does not affect the output, but I prefer to avoid the warning entirely.

   ---

   

   Sjors commented at 8:05 am on September 3, 2025:

   The rest of this project follows the mkdir build, cd build pattern, so seems fine to stick to that.

   The following does build for me on macOS:

   0cmake -B build
   1cmake --build build --target mpexample
   

   But then the example itself won’t work:

   0% build/example/mpexample
   1execvp failed: No such file or directory
   2libc++abi: terminating due to uncaught exception of type std::runtime_error: IPC client method call interrupted by disconnect.
   3zsh: abort      build/example/mpexample
   

   ---

   

   ryanofsky commented at 8:59 pm on September 3, 2025:

   In commit “doc: correct the build instructions for example” (b6d3dc44194c62e6baab8315266c0c745f61036b)

   Hmm, this all seems ok, but the PWD thing seems like something that could be followed up later. Would want to understand where exactly the warning is coming from and avoid it, maybe by unsetting PWD. @Sjors I think probably the reason you saw that error was because you built the mpexample target not mpexamples. mpexample is just the main example binary but it depends on mpcalculator and mpprinter. mpexamples is a target that builds all 3 binaries. This could also deserve a followup to be less confusing.

   ---

   

   Sjors commented at 7:24 am on September 4, 2025:

   You’re right, --target mpexamples (with an “s”) works:

   0% build/example/mpexample
   1Enter the equation, or "exit" to quit: How much is the fish?
   2mpprinter: Wow How much is the fish?, that's a tough one.
   

7. 
   ismaelsadeeq commented at 7:55 am on September 3, 2025: member

   Concept ACK I also come across the issue yesterday while trying to build the example
8. 
   Sjors commented at 8:05 am on September 3, 2025: member

   ACK b6d3dc44194c62e6baab8315266c0c745f61036b
9. DrahtBot requested review from ismaelsadeeq on Sep 3, 2025
10. 
    ismaelsadeeq commented at 8:10 am on September 3, 2025: member

    ACK b6d3dc44194c62e6baab8315266c0c745f61036b
11. ryanofsky approved
12. 
    ryanofsky commented at 9:01 pm on September 3, 2025: collaborator

    Code review ACK b6d3dc44194c62e6baab8315266c0c745f61036b. Thanks for the fix!
13. 
    ryanofsky commented at 9:02 pm on September 3, 2025: collaborator

    Note: this documentation has been broken since #136 which renamed example target to mpexamples
14. ryanofsky merged this on Sep 4, 2025
15. ryanofsky closed this on Sep 4, 2025

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16. ryanofsky referenced this in commit a334bbe9b7 on Sep 5, 2025
17. fanquake referenced this in commit 9c6fa07b12 on Sep 8, 2025
18. Sjors referenced this in commit 132621fc01 on Sep 23, 2025

Contributors
Eunovo DrahtBot ismaelsadeeq Sjors ryanofsky