Who Needs Main() Anyway?

http://rachelbythebay.com/w/2023/01/20/mainless/

by HieronymusBosch • 4 years ago

30 14 4 years ago

rachelbythebay.com

jeffreygoesto• 4 years ago

Sigh. Wait until she learns about the static initialization order fiasco...

moloch-hai3• 4 years ago

She knows. Code where it matters is wrong.

sargstuff3• 4 years ago

Sounds like a have to C it to believe it.

xjwm2• 4 years ago

I've written code like this in C to create library functions that will be linked in to other projects, but where there is no 'main' function in the C file. Do people use C++ the same way, or is it best practice to include 'main?'

MathMonkeyMan• 4 years ago

It's the same as in C. The observation here is that variables with static storage duration can be initialized by running user code before main() begins.

xjwm2• 4 years ago

Oh! Thank you. That makes much more sense now.

colejohnson66• 4 years ago

It’s also the same in .NET. If your Main() function references types that have a static constructor, the constructors could run before Main().

It’s a surprising thing when one first discovers it, but it makes a lot of sense.

moloch-hai3• 4 years ago

It didn't crash until after its work was done. It could even have trapped the segfault and exited cleanly.

marssaxman• 4 years ago

Couldn't just call exit(0)?

moloch-hai3• 4 years ago

Maybe, or _exit().

0xcafefood• 4 years ago

A more useful application of this same idea ("you can do stuff during static initialization") is for building a static registry.

https://artificial-mind.net/blog/2020/10/17/static-registrat... gives a good overview.

sargstuff3• 4 years ago

[1] p.99 information might be of interest

   cc -Wl,-m main.c > main.linker.map

related search terms: _crtStartUp crt0 crt1

[1] https://progforperf.github.io/Expert_C_Programming.pdf

rramadass• 4 years ago

Is this what passes for "technical know-how" nowadays?

Just read Hongjiu Lu's classic paper ELF: From The Programmer's Perspective to get an idea of how everything comes together in C/C++ land.

sargstuff3• 4 years ago

But in today's non-programmer post-covid world, ELF is seasonal, COFF is year round.

edit: COFF phoneticly eqivalent to cough.

Who Needs Main() Anyway?

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