[RFC] Standardizing Taichi Error Types

[lin-hitonami]

Motivation

In the taichi code base, there are too many kinds of error types like KernelDefError, KernelArgError, InvalidOperationError, TaichiSyntaxError, RuntimeError, TypeError, ValueError, and even Exception. Moreover, there is no standard on which error should be raised in which situation. So, we should standardize the error types.

Goals

• Make rules on when should we use which error type.
• Let the error types inherit the corresponding python errors.
• Change the errors in the code base to comply with the rules.

Proposal

• TaichiCompilationError
  • The base class of all errors generated in the compilation process.
  • Used when an error in the compilation process occurs that does not fit in other errors.
• TaichiTypeError
  • Inherits TaichiCompilationError and TypeError
  • Used when a type error is detected when performing type checks.
• TaichiSyntaxError
  • Inherits TaichiCompilationError and SyntaxError
  • Used when encountering a syntax that taichi does not support.
• TaichiNameError
  • Inherits TaichiCompilationError and NameError
  • Used when taichi encounters a undefined name.
• TaichiRuntimeError
  • Inherits RuntimeError
  • Used when a compiled taichi program fails to execute.
• TaichiRuntimeTypeError
  • Inherits TaichiRuntimeError and TypeError
  • Used when the type of an argument does not match the corresponding kernel parameter.

[k-ye]

Looks great!

I suggest not to TaichiTypeError inherit from TaichiCompilationError. It is possible to produce a type error at compile time. E.g. your kernel takes in a vec3, but a vec4 is passed in.

[strongoier]

Looks great!

I suggest not to TaichiTypeError inherit from TaichiCompilationError. It is possible to produce a type error at compile time. E.g. your kernel takes in a vec3, but a vec4 is passed in.

I would consider this case as a TaichiRuntimeError because it doesn't belong to the Taichi compilation process. Instead, the situation is that the compiled program fails to execute.

[lin-hitonami]

Maybe we can add TaichiRuntimeTypeError that inherits TaichiRuntimeError and TypeError for this case?

[strongoier]

Maybe we can add TaichiRuntimeTypeError that inherits TaichiRuntimeError and TypeError for this case?

Sounds good to me.