Question about the requirements for defining UNICODE and _UNICODE on Win32

[slabko]

I’m a bit confused that UNICODE is defined by Poco::Foundation publicly, with no way to turn it off.

As a result, every library that links against Poco::Foundation is effectively forced to have UNICODE and _UNICODE defined. While using UNICODE is generally recommended for Win32 projects, this isn’t always the case, there are situations where developers prefer to build applications in ANSI mode.

I also noticed that Poco builds fine even when UNICODE and _UNICODE are not enabled.

So my questions are:

1. Is it a strict requirement that Poco be built with UNICODE and _UNICODE on Win32?
2. Is it a strict requirement that client projects have these definitions?

For reference, this is the line where UNICODE is defined:
https://github.com/pocoproject/poco/blob/poco-1.14.2-release/Foundation/CMakeLists.txt#L140

[andrewauclair]

I don't know the answer. I think I would like to know as well. But, if you're looking for a workaround, this is what I do to remove UNICODE and _UNICODE from the Poco targets in my CMakeLists.txt:

function(remove_unicode)
	message(STATUS "remove UNICODE from " ${ARGV0})
	get_target_property(defs ${ARGV0} COMPILE_DEFINITIONS)
	list(FILTER defs EXCLUDE REGEX [[^UNICODE$]])
	list(FILTER defs EXCLUDE REGEX [[^_UNICODE$]])
	set_property(TARGET ${ARGV0} PROPERTY COMPILE_DEFINITIONS ${defs})
	
	get_target_property(defs ${ARGV0} INTERFACE_COMPILE_DEFINITIONS)
	list(FILTER defs EXCLUDE REGEX [[^UNICODE$]])
	list(FILTER defs EXCLUDE REGEX [[^_UNICODE$]])
	set_property(TARGET ${ARGV0} PROPERTY INTERFACE_COMPILE_DEFINITIONS ${defs})
	
	get_target_property(defs ${ARGV0} COMPILE_DEFINITIONS_DEBUG)
	list(FILTER defs EXCLUDE REGEX [[^UNICODE$]])
	list(FILTER defs EXCLUDE REGEX [[^_UNICODE$]])
	set_property(TARGET ${ARGV0} PROPERTY COMPILE_DEFINITIONS_DEBUG ${defs})
	
	get_target_property(defs ${ARGV0} COMPILE_DEFINITIONS_RELEASE)
	list(FILTER defs EXCLUDE REGEX [[^UNICODE$]])
	list(FILTER defs EXCLUDE REGEX [[^_UNICODE$]])
	set_property(TARGET ${ARGV0} PROPERTY COMPILE_DEFINITIONS_RELEASE ${defs})
endfunction()

if (MSVC)
	remove_unicode(Util)
	remove_unicode(Foundation)
	remove_unicode(Data)
	remove_unicode(DataSQLite)
	remove_unicode(XML)
	remove_unicode(JSON)
	remove_unicode(Net)
endif()