Add common Lua functions, use a Lua function in %python_provide

macros.python

@@ -53,43 +53,32 @@
 }
 
 %python_provide() %{lua:
+  local python = require "fedora.srpm.python"
   function string.starts(String,Start)
     return string.sub(String,1,string.len(Start))==Start
   end
-  package = rpm.expand("%{?1}")
-  vr = rpm.expand("%{?epoch:%{epoch}:}%{version}-%{release}")
+  local package = rpm.expand("%{?1}")
+  local vr = rpm.expand("%{?epoch:%{epoch}:}%{version}-%{release}")
+  local altnames = python.python_altnames(package)
   if (string.starts(package, "python3-")) then
-    print("\\nProvides: python-")
-    print(string.sub(package,9,string.len(package)))
-    print(" = ")
-    print(vr)
-    print("\\nProvides: python" .. rpm.expand("%{__default_python3_pkgversion}") .. "-")
-    print(string.sub(package,9,string.len(package)))
-    print(" = ")
-    print(vr)
+    for i, altname in ipairs(altnames) do
+      print("\\nProvides: " .. altname .. " = " .. vr)
+    end
     --Obsoleting the previous default python package (if it doesn't have isa)
     if (string.sub(package, "-1") ~= ")") then
       print("\\nObsoletes: python-")
       print(string.sub(package,9,string.len(package)))
-      print(" < ")
-      print(vr)
+      print(" < " .. vr)
     end
   elseif (string.starts(package, "python" .. rpm.expand("%{__default_python3_pkgversion}") .. "-")) then
-    print("\\nProvides: python-")
-    l = 8 + string.len(rpm.expand("%{__default_python3_pkgversion}"))
-    print(string.sub(package,l,string.len(package)))
-    print(" = ")
-    print(vr)
-    print("\\nProvides: python3-")
-    print(string.sub(package,l,string.len(package)))
-    print(" = ")
-    print(vr)
+    for i, altname in ipairs(altnames) do
+      print("\\nProvides: " .. altname .. " = " .. vr)
+    end
     --Obsoleting the previous default python package (if it doesn't have isa)
     if (string.sub(package, "-1") ~= ")") then
       print("\\nObsoletes: python-")
-      print(string.sub(package,l,string.len(package)))
-      print(" < ")
-      print(vr)
+      print(string.sub(package,10,string.len(package)))
+      print(" < " .. vr)
     end
   elseif (string.starts(package, "python")) then
     --No unversioned provides as other python3 cases are not the default

python-rpm-macros.spec

@@ -3,7 +3,7 @@ Version:        3.8
 Release:        4%{?dist}
 Summary:        The common Python RPM macros
 
-# macros: MIT, compileall2.py: PSFv2
+# macros and lua: MIT, compileall2.py: PSFv2
 License:        MIT and Python
 Source0:        macros.python
 Source1:        macros.python-srpm
@@ -11,6 +11,7 @@ Source2:        macros.python2
 Source3:        macros.python3
 Source4:        macros.pybytecompile
 Source5:        https://github.com/fedora-python/compileall2/raw/v0.7.1/compileall2.py
+Source6:        python.lua
 
 BuildArch:      noarch
 # For %%python3_pkgversion used in %%python_provide and compileall2.py
@@ -64,6 +65,9 @@ mkdir -p %{buildroot}%{_rpmconfigdir}/redhat
 install -m 644 %{SOURCE5} \
   %{buildroot}%{_rpmconfigdir}/redhat/
 
+mkdir -p %{buildroot}%{_rpmluadir}/fedora/srpm
+install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm %{SOURCE6}
+
 %files
 %{rpmmacrodir}/macros.python
 %{rpmmacrodir}/macros.pybytecompile
@@ -71,6 +75,7 @@ install -m 644 %{SOURCE5} \
 %files -n python-srpm-macros
 %{rpmmacrodir}/macros.python-srpm
 %{_rpmconfigdir}/redhat/compileall2.py
+%{_rpmluadir}/fedora/srpm/python.lua
 
 %files -n python2-rpm-macros
 %{rpmmacrodir}/macros.python2

python.lua

@@ -0,0 +1,32 @@
+-- Convenience Lua functions that can be used within Python srpm/rpm macros
+
+-- Determine alternate names provided from the given name.
+-- Used in pythonname provides generator, python_provide and py_provides.
+-- There are 2 rules:
+--  python3-foo  -> python-foo, python3X-foo
+--  python3X-foo -> python-foo, python3-foo
+-- There is no python-foo -> rule, python-foo packages are version agnostic.
+-- Returns a table/array with strings. Empty when no rule matched.
+local function python_altnames(name)
+  local xy = rpm.expand('%{__default_python3_pkgversion}')
+  local altnames = {}
+  local replaced
+  -- NB: dash needs to be escaped!
+  if name:match('^python3%-') then
+    for i, prefix in ipairs({'python-', 'python' .. xy .. '-'}) do
+      replaced = name:gsub('^python3%-', prefix)
+      table.insert(altnames, replaced)
+    end
+  elseif name:match('^python' .. xy .. '%-') then
+    for i, prefix in ipairs({'python-', 'python3-'}) do
+      replaced = name:gsub('^python' .. xy .. '%-', prefix)
+      table.insert(altnames, replaced)
+    end
+  end
+  return altnames
+end
+
+
+return {
+  python_altnames = python_altnames,
+}