Mojo module

defines

Implements functions for retrieving compile-time defines.

You can use these functions to set parameter values or runtime constants based on name-value pairs defined on the command line. For example:

  from std.sys import is_defined

  comptime float_type = DType.float32 if is_defined["FLOAT32"]() else DType.float64

  # Use `float_type` as a constant.

And on the command line:

  mojo -D FLOAT32 main.mojo

For more information, see the Mojo build docs. The mojo run command also supports the -D option.

You can import these APIs from the sys package. For example:

from std.sys import is_defined

Functions

get_defined_bool: Try to get a boolean-valued define. Compilation fails if the name is not defined or the value is not a recognized boolean (True, False, 1, 0, on, off).
get_defined_dtype: Try to get a DType-valued define. If the name is not defined, return a default value instead.
get_defined_int: Try to get an integer-valued define. Compilation fails if the name is not defined.
get_defined_string: Try to get a string-valued define. Compilation fails if the name is not defined.
is_defined: Return true if the named value is defined.

Functions​

Functions