How to Obtain Type Names in C Templates for Parse Error Reporting?

How to Obtain Type Names in C Templates for Parse Error Reporting

When encountering errors while parsing text data files, it is crucial to provide informative messages to non-programmers, stating the issue and the data file location where the error occurred. While extracting file, section, and key names is straightforward, obtaining the data type that the template function is parsing to is not immediately apparent.

To address this need, two approaches can be considered:

Runtime Type Identification with typeid

catch(...)throw ParseError(file, section, key, it->second, typeid(T).name());<br>

This approach utilizes the typeid operator to retrieve the type name during runtime. However, it may incur runtime overhead if an exception is thrown, which is undesirable for code that is executed frequently.

Compile-Time Type Name Macros

An alternative approach involves defining type name macros in a separate header file:

#pragma once
template<typename T> const wchar_t *GetTypeName();

#define DEFINE_TYPE_NAME(type, name) \
    template<>const wchar_t *GetTypeName<type>(){return name;}

These macros can be used to specify the type names for all desired types in their respective header files. The linker will automatically resolve the appropriate template specialization based on the defined types, or throw an error if a required type is missing.

This compile-time approach eliminates any runtime overhead and ensures that all required type names are defined at compile time. It also allows for easy addition of new types in the future.

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