Array of function pointers | Zig Programming Language | Page 1

raven oracle Oct 2, 2024, 6:30 PM

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pub const OpcodeStep = fn (*OpcodeBuilder) void;
pub const test = struct { steps: []*OpcodeStep };

and then defining it:

        .steps = &[_]OpcodeStep{
            OpcodeBuilder.loadModrm,
        },

and i get
expected type '[1]*fn (*system.def.OpcodeBuilder) void', found '[1]fn (*system.def.OpcodeBuilder) void' this seems like a pretty easy fix but im not really sure how to appease this issue. any help would be appreciated!

teal zodiac Oct 2, 2024, 6:32 PM

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The type of steps should be []*const OpcodeBuilder, not []*OpcodeBuilder

raven oracle Oct 2, 2024, 6:34 PM

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i tried that first, and it gave me error: expected type '[1]*fn (*system.def.OpcodeBuilder) void', found '[1]fn (*system.def.OpcodeBuilder) void'

teal zodiac Oct 2, 2024, 6:34 PM

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isn't that the same error you sent above?

raven oracle Oct 2, 2024, 6:35 PM

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yes sorry i forgot i also modified it so &[_]*OpcodeStep which means it gave error: expected type '*fn (*system.def.OpcodeBuilder) void', found '*const fn (*system.def.OpcodeBuilder) void'

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at this point i was unsure of how to proceed

teal zodiac Oct 2, 2024, 6:35 PM

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pub const OpcodeStep = fn (*OpcodeBuilder) void;
pub const test = struct { steps: []*const OpcodeStep };

        .steps = &[_]*const OpcodeStep{
            &OpcodeBuilder.loadModrm,
        },

raven oracle Oct 2, 2024, 6:35 PM

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oh ty the part i was missing was *const

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i tried const*

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and that is not ok

gloomy scarab Oct 2, 2024, 6:36 PM

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you need both, youre initializing it with a const array pointer

raven oracle Oct 2, 2024, 6:36 PM

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still doesn't work though 😅

gloomy scarab Oct 2, 2024, 6:36 PM

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[]const *const OpcodeStep

raven oracle Oct 2, 2024, 6:37 PM

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ty.

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that got it

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that is a bit of a huge hole in my knowledge though

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is there a relevant part of the language spec?

limpid quest Oct 2, 2024, 6:38 PM

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https://ziglang.org/documentation/master/#Functions

// Function pointers are prefixed with *const .

There is a difference between a function body and a function pointer. Function bodies are comptime-only types while function Pointers may be runtime-known.

raven oracle Oct 2, 2024, 6:39 PM

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ty. you know i read that and just internalized it as const*.

#Array of function pointers