Add optional versions argument to require()

src/base/_foundation.lua

@@ -4,6 +4,9 @@
 ---
 
 	premake = premake or {}
+	premake._VERSION = _PREMAKE_VERSION
+	package.loaded["premake"] = premake
+
 	premake.modules = {}
 	premake.extensions = premake.modules
 
@@ -101,6 +104,10 @@
 ---
 
 	function p.checkVersion(version, checks)
+		if not version then
+			return false
+		end
+
 		local function parse(str)
 			local major, minor, patch, dev = str:match("^(%d+)%.?(%d*)%.?(%d*)(.-)$")
 			major = tonumber(major) or 0
@@ -142,6 +149,9 @@
 			elseif check:startswith("<") then
 				func = lt
 				check = check:sub(2)
+			elseif check:startswith("=") then
+				func = eq
+				check = check:sub(2)
 			else
 				func = ge
 			end

src/base/globals.lua

@@ -55,3 +55,29 @@
 			return dofile(fname)
 		end
 	end
+
+
+
+---
+-- Extend require() with a second argument to specify the expected
+-- version of the loaded module. Raises an error if the version criteria
+-- are not met.
+--
+-- @param modname
+--    The name of the module to load.
+-- @param versions
+--    An optional version criteria string; see premake.checkVersion()
+--    for more information on the format.
+-- @return
+--    If successful, the loaded module, which is also stored into the
+--    global package.loaded table.
+---
+
+	premake.override(_G, "require", function(base, modname, versions)
+		local mod = base(modname)
+		if mod and versions and not premake.checkVersion(mod._VERSION, versions) then
+			error(string.format("module %s %s does not meet version criteria %s",
+				modname, mod._VERSION or "(none)", versions), 3)
+		end
+		return mod
+	end)

src/host/premake.c

@@ -14,7 +14,7 @@
 #endif
 
 
-#define VERSION        "HEAD"
+#define VERSION        "5.0.0-dev"
 #define COPYRIGHT      "Copyright (C) 2002-2015 Jason Perkins and the Premake Project"
 #define PROJECT_URL    "https://github.com/premake/premake-core/wiki"
 #define ERROR_MESSAGE  "Error: %s\n"

tests/base/test_versions.lua

@@ -169,3 +169,11 @@
 		test.isfalse(p.checkVersion("2.2.0.0", ">=1.0 <2.0"))
 	end
 
+
+--
+-- If there is no version information, fails.
+--
+
+	function suite.fail_onNoVersion()
+		test.isfalse(p.checkVersion(nil, "1.0"))
+	end