Running a program: pep-run

pep-run builds a program and runs it straight away, the way python script.py runs a script: there is no -o to choose and no executable to clean up. pepper run runs it with the same arguments.

pepper run hello.pep               # build hello.pep, then run it
pepper run args.pep a b            # main sees a and b
pepper run -O2 -D FAST main.pep    # build options go before the file
pepper run -- --port 8080          # the project pep.toml describes
pepper run --entry bench tool.pep  # start in bench() instead of main()

pep-run [BUILD OPTIONS] [<entry.pep>] [ARGUMENTS]...
pep-run [BUILD OPTIONS] -- [ARGUMENTS]...

Arguments

• The arguments before the entry file are pep-build’s options (-O2, -D NAME, -I DIR, -l LIB, …; see The compiler: pep-build), and they apply as they do for pepper build, as do a project’s [build] table and its [Link] libraries.
• The entry file is the first argument that ends in .pep and does not start with -. Everything after it goes to the program’s main, options included: in pepper run tool.pep --help, --help is the program’s.
• -- ends the build options too. With no entry file, pep-run builds the project whose pep.toml is in the current folder or the nearest folder above it, as pepper build does, and the arguments after -- go to it.
• The options that choose what pep-build writes are not taken: -o, --lib, --test, --target and the --emit-... options are an error that exits with status 2.

How it runs

1. pep-run runs pep-build (beside pep-run, else on the PATH) to build the program into a folder of its own: <Pepper home>/run/<key>/<entry stem> (main for a project), where the key is a hash of the current folder, the build options and the entry file, and the Pepper home is PEPPER_HOME, else ~/.pepper (%LOCALAPPDATA%\pepper on Windows; see Toolchains: pep-install).
2. The build cache is PEPPER_CACHE_DIR when it is set, else <Pepper home>/cache, which every run shares, so the standard library is compiled once for all your scripts. When nothing changed, pep-build finds the program up to date and the run starts at once; when something did, only what changed is compiled again.
3. A compile error is reported exactly as pepper build reports it, nothing runs, and pep-run exits with pep-build’s status.
4. Otherwise the program runs in the folder pep-run was started in, so a relative path such as data.txt is found there, with pep-run’s standard input, output and error. On Linux and macOS it takes pep-run’s place, so signals such as Ctrl-C reach it directly; on Windows pep-run waits for it. Either way pep-run exits with the program’s exit status.

Two runs of one program at the same time are safe: the linker writes the executable to a temporary file and renames it into place, so neither ever starts a half-written program.

The run folders are not removed on their own; delete <Pepper home>/run to reclaim the space.