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README: Add information on flushing for printf-style debugging #198

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Oct 19, 2021
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README: Add information on flushing for printf-style debugging #198

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eca7eaa
Git ignore v8go.test
dylanahsmith Oct 19, 2021
2e217d5
README: Add information on flushing for printf-style debugging
dylanahsmith Oct 19, 2021
b0859e0
Update README.md
Oct 19, 2021
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2 changes: 2 additions & 0 deletions .gitignore
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Expand Up @@ -8,3 +8,5 @@
deps/darwin-x86_64/libv8_debug.a

c.out

/v8go.test
13 changes: 13 additions & 0 deletions README.md
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Expand Up @@ -190,6 +190,19 @@ and select your pushed branch eg. `v8_7_upgrade`.
1) Once built, this should open 3 PRs against your branch to add the `libv8.a` for Linux, macOS and Windows; merge
these PRs into your branch. You are now ready to raise the PR against `master` with the latest version of V8.

### Flushing after C/C++ standard library printing for debugging

When using the C/C++ standard library functions for printing (e.g. `printf`), then the output will be buffered by default.
This can cause some confusion, especially because the test binary (created through `go test`) does not flush the buffer
at exit (at the time of writing). When standard output is the terminal, then it will use line buffering and flush when
a new line is printed, otherwise (e.g. if the output is redirected to a pipe or file) it will be fully buffered and not even
flush at the end of a line. When the test binary is executed through `go test .` (e.g. instead of
separately compiled with `go test -c` and run with `./v8go.test`) Go may redirect standard output internally, resulting in
standard output being fully buffered.

A simple way to avoid this problem is to flush the standard output stream after printing with the `fflush(stdout);` statement.
Not relying on the flushing at exit can also help ensure the output is printed before a crash.

### Formatting

Go has `go fmt`, C has `clang-format`. Any changes to the `v8go.h|cc` should be formated with `clang-format` with the
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