Roland Ver. 4.5 Informações Técnicas descarregar pdf (Página 106)

96 GNU make

The syntax of the flavor function is:

$(flavor variable)

Note that variable is the name of a variable to inquire about, not a reference to that

variable. Therefore you would not normally use a ‘$’ or parentheses when writing it. (You

can, however, use a variable reference in the name if you want the name not to be a

constant.)

The result of this function is a string that identiﬁes the ﬂavor of the variable variable:

‘undefined’

if variable was never deﬁned.

‘recursive’

if variable is a recursively expanded variable.

‘simple’

if variable is a simply expanded variable.

8.12 Functions That Control Make

These functions control the way make runs. Generally, they are used to provide information

to the user of the makeﬁle or to cause make to stop if some sort of environmental error is

detected.

$(error text...)

Generates a fatal error where the message is text. Note that the error is gen-

erated whenever this function is evaluated. So, if you put it inside a recipe or

on the right side of a recursive variable assignment, it won’t be evaluated until

later. The text will be expanded before the error is generated.

For example,

ifdef ERROR1

$(error error is $(ERROR1))

endif

will generate a fatal error during the read of the makeﬁle if the make variable

ERROR1 is deﬁned. Or,

ERR = $(error found an error!)

.PHONY: err

err: ; $(ERR)

will generate a fatal error while make is running, if the err target is invoked.

$(warning text...)

This function works similarly to the error function, above, except that make

doesn’t exit. Instead, text is expanded and the resulting message is displayed,

but processing of the makeﬁle continues.

The result of the expansion of this function is the empty string.

$(info text...)

This function does nothing more than print its (expanded) argument(s) to stan-

dard output. No makeﬁle name or line number is added. The result of the

expansion of this function is the empty string.

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