From aab08e87d24b8e264ec6a35014776ba79e598355 Mon Sep 17 00:00:00 2001
From: Dale Sedivec <dale@codefu.org>
Date: Thu, 30 Mar 2023 18:56:31 -0500
Subject: [PATCH] Make el-patch-get use the only variant by default

I make significant use of `el-patch-validate` non-interactively in my
init file.  These usages broke when I updated to the latest version of
el-patch, because an invocation that used to work such as

    (el-patch-validate 'some-function 'defun 'nomsg)

was now unable to look up the patch I had just applied to
`some-function`.  I believe this is happening because
`el-patch-validate` was allowing you to omit `variant`, and `nil` is
not a possible variant.  From reading the code, I believe all variants
will be a cons of `(advice name)`.  Therefore when `el-patch-validate`
calls `(el-patch-get 'some-function 'defun nil)`, it will never get a
result, and `el-patch-validate` will always fail.

`(nil)` *could* perhaps be called "the default variant", but I didn't
see it hard coded anywhere else in el-patch, so I wasn't about to
start here.  Instead, I made `el-patch-get` (which also makes the
`variant` argument optional) use the one and only variant present for
the given name.  If more than one variant is present, and the caller
didn't supply `variant`, `el-patch-get` now signals an error.  I
picked `wrong-type-argument` because it was the standard error closest
in spirit to what I was trying to convey, and I didn't feel that this
case called for defining a whole new error.
---
 CHANGELOG.md |  7 +++++++
 el-patch.el  | 24 ++++++++++++++++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 848b992..7ec48ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,13 @@
 All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog].
 
+## Unreleased
+### Enhancements
+* `el-patch-get` will try and return the only variant of a function
+  when you don't provide a specific `variant`.  This makes it so that
+  you can call functions such as `el-patch-validate` non-interactively
+  without providing `variant`.
+
 ## 3.0 (released 2022-04-17)
 ### Breaking changes
 * The arguments to `el-patch-feature` after the feature name are no
diff --git a/el-patch.el b/el-patch.el
index a1dfc99..365f425 100644
--- a/el-patch.el
+++ b/el-patch.el
@@ -1059,10 +1059,26 @@ and TYPE is a symbol `defun', `defmacro', etc. If the patch could
 not be found, return nil.
 
 If VARIANT is provided, select that variant of the patch. This is
-useful only if patches were defined using `el-patch-variant'."
-  (condition-case nil
-      (gethash variant (gethash type (gethash name el-patch--patches)))
-    (error nil)))
+useful only if patches were defined using `el-patch-variant'.  If
+VARIANT is not provided and more than one variant is present for
+the patch, `wrong-type-argument' is signaled."
+  (let* ((types (gethash name el-patch--patches))
+         (variants (and types (gethash type types))))
+    (cond
+     ((not variants)
+      nil)
+     (variant
+      (gethash variant variants))
+     (t
+      (let (only-value)
+        (maphash (lambda (_ value)
+                   (when only-value
+                     (error 'wrong-type-argument
+                            "Must choose a variant for `%s' type %s."
+                            name type))
+                   (setq only-value value))
+                 variants)
+        only-value)))))
 
 (defun el-patch--select-patch ()
   "Use `completing-read' to select a patched function.