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What are C++20 Modules and how do they replace traditional header files? [Discussion #2]

CSharpNinja
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7mo ago · Dec 25, 2025 5:15 PM
#1
How do C++20 Modules (.ixx / .cppm) compare to traditional .h and .cpp file structures? Do they actually eliminate header guards and speed up build times?
CSharpNinja · Senior .NET Developer
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SharpShooter_x
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7mo ago · Dec 25, 2025 7:48 PM
#2
Modules compile once into a binary Module Interface File (BMI / IFC). When another translation unit imports the module (import MyModule;), the compiler loads the pre-parsed AST directly instead of re-tokenizing thousands of lines of text! Macro leaks across files are completely prevented.
SharpShooter_x · Unity C# Modder
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BytePusher
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7mo ago · Dec 25, 2025 8:48 PM
#3
Build times on large projects drop dramatically because header parsing is no longer duplicated across every single .cpp file.
BytePusher · Memory & Performance
Zero-allocation C# code using Span<T>, Memory<T>, and Unsafe...