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externals/vcpkg/docs/maintainers/vcpkg_list.md

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+# vcpkg_list
+
+The latest version of this document lives in the [vcpkg repo](https://github.com/Microsoft/vcpkg/blob/master/docs/maintainers/vcpkg_list.md).
+
+A replacement for CMake's `list()` function, which correctly handles elements
+with internal semicolons (in other words, escaped semicolons).
+Use `vcpkg_list()` instead of `list()` whenever possible.
+
+```cmake
+vcpkg_list(SET <out-var> [<element>...])
+vcpkg_list(<COMMAND> <list-var> [<other-arguments>...])
+```
+
+In addition to all of the commands from `list()`, `vcpkg_list` adds
+a `vcpkg_list(SET)` command.
+This command takes its arguments, escapes them, and then concatenates
+them into a list; this should be used instead of `set()` for setting any
+list variable.
+
+Otherwise, the `vcpkg_list()` function is the same as the built-in
+`list()` function, with the following restrictions:
+
+- `GET`, `REMOVE_ITEM`, and `REMOVE_AT` support only one index/value
+- `POP_BACK` and `POP_FRONT` do not support getting the value into
+  another out variable. Use C++ style `GET` then `POP_(BACK|FRONT)`.
+- `FILTER` and `TRANSFORM` are unsupported.
+
+See the [CMake documentation for `list()`](https://cmake.org/cmake/help/latest/command/list.html)
+for more information.
+
+## Notes: Some Weirdnesses
+
+The most major weirdness is due to `""` pulling double-duty as "list of zero elements",
+and "list of one element, which is empty". `vcpkg_list` always uses the former understanding.
+This can cause weird behavior, for example:
+
+```cmake
+set(lst "")
+vcpkg_list(APPEND lst "" "")
+# lst = ";"
+```
+
+This is because you're appending two elements to the empty list.
+One very weird behavior that comes out of this would be:
+
+```cmake
+set(lst "")
+vcpkg_list(APPEND lst "")
+# lst = ""
+```
+
+since `""` is the empty list, we append the empty element and end up with a list
+of one element, which is empty. This does not happen for non-empty lists;
+for example:
+
+```cmake
+set(lst "a")
+vcpkg_list(APPEND lst "")
+# lst = "a;"
+```
+
+only the empty list has this odd behavior.
+
+## Examples
+
+### Creating a list
+
+```cmake
+vcpkg_list(SET foo_param)
+if(DEFINED arg_FOO)
+    vcpkg_list(SET foo_param FOO "${arg_FOO}")
+endif()
+```
+
+### Appending to a list
+
+```cmake
+set(OPTIONS -DFOO=BAR)
+if(VCPKG_TARGET_IS_WINDOWS)
+    vcpkg_list(APPEND OPTIONS "-DOS=WINDOWS;FOO")
+endif()
+```
+
+### Popping the end off a list
+
+```cmake
+if(NOT list STREQUAL "")
+    vcpkg_list(GET list end -1)
+    vcpkg_list(POP_BACK list)
+endif()
+```
+
+## Source
+[scripts/cmake/vcpkg\_list.cmake](https://github.com/Microsoft/vcpkg/blob/master/scripts/cmake/vcpkg_list.cmake)