glossary: add definitions for dereference & peel
PATCH 1/1 glossary: add definitions for dereference & peel
From: Victoria Dye <[email protected]>
Add 'gitglossary' definitions for "dereference" (as it used for both symrefs and objects) and "peel". These terms are used in options and documentation throughout Git, but they are not clearly defined anywhere and the behavior they refer to depends heavily on context. Provide explicit definitions to clarify existing documentation to users and help contributors to use the most appropriate terminology possible in their additions to Git.
Update other definitions in the glossary that use the term "dereference" to link to 'def_dereference'.
---
glossary: add definitions for dereference & peel
As promised in [1], this patch adds definitions for "peel" and "dereference" in the glossary, based on how they're currently used throughout Git. As a result, the definitions are somewhat broad (although I did my best to explicitly describe the different contexts in which they're used). My hope is that this will at least reduce confusion around this terminology. These definitions can also serve as a starting point if, in the future, another contributor wants to deprecate certain usages of these terms to make them less ambiguous.
* Victoria
[1]
https://lore.kernel.org/git/[email protected]/
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1610%2Fvdye%2Fvdye%2Fglossary-peel-dereference-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1610/vdye/vdye/glossary-peel-dereference-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1610
Documentation/glossary-content.txt | 50 +++++++++++++++++++++--------- 1 file changed, 36 insertions(+), 14 deletions(-)
Documentation/glossary-content.txt +36 -14
@@ -98,9 +98,8 @@ to point at the new commit. revision. [[def_commit-ish]]commit-ish (also committish):: - A <<def_commit_object,commit object>> or an - <<def_object,object>> that can be recursively dereferenced to - a commit object. + A <<def_commit_object,commit object>> or an <<def_object,object>> that + can be recursively <<def_dereference,dereferenced>> to a commit object. The following are all commit-ishes: a commit object, a <<def_tag_object,tag object>> that points to a commit
@@ -125,6 +124,24 @@ to point at the new commit. dangling object has no references to it from any reference or <<def_object,object>> in the <<def_repository,repository>>. +[[def_dereference]]dereference:: + Referring to a <<def_symref,symbolic ref>>: the action of accessing the + <<def_ref,reference>> pointed at by a symbolic ref. Recursive + dereferencing involves repeating the aforementioned process on the + resulting ref until a non-symbolic reference is found. ++ +Referring to a <<def_tag_object,tag object>>: the action of accessing the +<<def_object,object>> a tag points at. Tags are recursively dereferenced by +repeating the operation on the result object until the result has either a +specified <<def_object_type,object type>> (where applicable) or any non-"tag" +object type. ++ +Referring to a <<def_commit_object,commit object>>: the action of accessing +the commit's tree object. Commits cannot be dereferenced recursively. ++ +Unless otherwise specified, "dereferencing" as it used in the context of Git +commands or protocols is implicitly recursive. + [[def_detached_HEAD]]detached HEAD:: Normally the <<def_HEAD,HEAD>> stores the name of a <<def_branch,branch>>, and commands that operate on the
@@ -444,6 +461,12 @@ exclude;; of the logical predecessor(s) in the line of development, i.e. its parents. +[[def_peel]]peel:: + Synonym for object <<def_dereference,dereference>>. Most commonly used + in the context of tags, where it refers to the process of recursively + dereferencing a <<def_tag_object,tag object>> until the result object's + <<def_object_type,type>> is something other than "tag". + [[def_pickaxe]]pickaxe:: The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore routines that help select changes that add or delete a given text
@@ -620,12 +643,11 @@ The most notable example is `HEAD`. copies of) commit objects of the contained submodules. [[def_symref]]symref:: - Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> - id itself, it is of the format 'ref: refs/some/thing' and when - referenced, it recursively dereferences to this reference. - '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic - references are manipulated with the linkgit:git-symbolic-ref[1] - command. + Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> id + itself, it is of the format 'ref: refs/some/thing' and when referenced, + it recursively <<def_dereference,dereferences>> to this reference. + '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic references + are manipulated with the linkgit:git-symbolic-ref[1] command. [[def_tag]]tag:: A <<def_ref,ref>> under `refs/tags/` namespace that points to an
@@ -661,11 +683,11 @@ The most notable example is `HEAD`. <<def_tree,tree>> is equivalent to a <<def_directory,directory>>. [[def_tree-ish]]tree-ish (also treeish):: - A <<def_tree_object,tree object>> or an <<def_object,object>> - that can be recursively dereferenced to a tree object. - Dereferencing a <<def_commit_object,commit object>> yields the - tree object corresponding to the <<def_revision,revision>>'s - top <<def_directory,directory>>. + A <<def_tree_object,tree object>> or an <<def_object,object>> that can + be recursively <<def_dereference,dereferenced>> to a tree object. + Dereferencing a <<def_commit_object,commit object>> yields the tree + object corresponding to the <<def_revision,revision>>'s top + <<def_directory,directory>>. The following are all tree-ishes: a <<def_commit-ish,commit-ish>>, a tree object,
base-commit: dadef801b365989099a9929e995589e455c51fed
Signature · 1 line
gitgitgadget
Quoted 6 lines · Victoria Dye via GitGitGadget
Documentation/glossary-content.txt +2
-0@@ -125,6 +124,24 @@ to point at the new commit. dangling object has no references to it from any reference or <<def_object,object>> in the <<def_repository,repository>>. +[[def_dereference]]dereference:: + Referring to a <<def_symref,symbolic ref>>: the action of accessing the
Documentation/glossary-content.txt to point at the new commit. · line 138
Quoted 10 lines
Documentation/glossary-content.txt +10
-0+ <<def_ref,reference>> pointed at by a symbolic ref. Recursive + dereferencing involves repeating the aforementioned process on the + resulting ref until a non-symbolic reference is found. ++ +Referring to a <<def_tag_object,tag object>>: the action of accessing the +<<def_object,object>> a tag points at. Tags are recursively dereferenced by +repeating the operation on the result object until the result has either a +specified <<def_object_type,object type>> (where applicable) or any non-"tag" +object type. ++
All of the above makes sense.
I would casually mention "peeling" here with cross reference, if I were writing this section. There already is enough cross reference in the other direction pointing this way.
Documentation/glossary-content.txt to point at the new commit. · line 140
Quoted 2 lines
Documentation/glossary-content.txt +2
-0+Referring to a <<def_commit_object,commit object>>: the action of accessing +the commit's tree object. Commits cannot be dereferenced recursively.
I personally consider this is weird misuse of the verb and is rarely used, but we see it in the description of tree-ish below.
Documentation/glossary-content.txt to point at the new commit. · line 143
Quoted 2 lines
Documentation/glossary-content.txt +2
-0+Unless otherwise specified, "dereferencing" as it used in the context of Git +commands or protocols is implicitly recursive.
Nice to see this spelled out like this.
Documentation/glossary-content.txt exclude;; · line 468
Quoted 9 lines
Documentation/glossary-content.txt +5
-0@@ -444,6 +461,12 @@ exclude;; of the logical predecessor(s) in the line of development, i.e. its parents. +[[def_peel]]peel:: + Synonym for object <<def_dereference,dereference>>. Most commonly used + in the context of tags, where it refers to the process of recursively + dereferencing a <<def_tag_object,tag object>> until the result object's + <<def_object_type,type>> is something other than "tag".
"object dereference" is not defined anywhere (yet). "Most commonly used in the context of tags" implies that objects other than tags can be "peeled" and "object dereference" is a word to refer to peeling either "commit" or "tag", but we would want to be a bit more clear and explicit. Let's either define "object dereference", or better yet, avoid saying "object dereference" here and instead say something like: "Synonym for dereference when used on tags and commits".
I've never seen "peel" used for commits, though. So another improvement might be to say "peel" is "an act of dereferencing a tag" here.
Thanks.
Quoted 3 lines · Junio C Hamano
I've never seen "peel" used for commits, though. So another improvement might be to say "peel" is "an act of dereferencing a tag" here.
I am reasonably sure I was the one who coined the term "peel", and the picture I had in mind when I used it was to peel an onion, which inherently was about unwrapping many levels repeatedly. I think that is why it felt strange to see "peel" used in the context of using a commit as a tree-ish, which (as your documentation update clearly said) is doable only once.
Documentation/glossary-content.txt exclude;; · line 468
Quoted 5 lines · Victoria Dye via GitGitGadget
+[[def_peel]]peel::
Documentation/glossary-content.txt +4
-0+ Synonym for object <<def_dereference,dereference>>. Most commonly used + in the context of tags, where it refers to the process of recursively + dereferencing a <<def_tag_object,tag object>> until the result object's + <<def_object_type,type>> is something other than "tag".
As a user I like that this is classified as a synonym. Because if I wanted to ask StackOverflow about how to get to the commit that a tag points to then I would use the term “dereference a tag”.
Signature · 1 line
Kristoffer Haugsbakk
PATCH v2 1/1 glossary: add definitions for dereference & peel
In reply to Victoria Dye via GitGitGadgetFrom: Victoria Dye <[email protected]>
Add 'gitglossary' definitions for "dereference" (as it used for both symrefs and objects) and "peel". These terms are used in options and documentation throughout Git, but they are not clearly defined anywhere and the behavior they refer to depends heavily on context. Provide explicit definitions to clarify existing documentation to users and help contributors to use the most appropriate terminology possible in their additions to Git.
Update other definitions in the glossary that use the term "dereference" to link to 'def_dereference'.
---
glossary: add definitions for dereference & peel
As promised in [1], this patch adds definitions for "peel" and "dereference" in the glossary, based on how they're currently used throughout Git. As a result, the definitions are somewhat broad (although I did my best to explicitly describe the different contexts in which they're used). My hope is that this will at least reduce confusion around this terminology. These definitions can also serve as a starting point if, in the future, another contributor wants to deprecate certain usages of these terms to make them less ambiguous.
* Victoria
[1]
https://lore.kernel.org/git/[email protected]/
Changes since V1
================
* Removed references to "peeling" a commit; the updated definition discusses "peeling" only in the context of tags.
* Added a cross-link from "dereference" to "peel" (one already existed for "peel" to "dereference").
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1610%2Fvdye%2Fvdye%2Fglossary-peel-dereference-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1610/vdye/vdye/glossary-peel-dereference-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1610
Range-diff vs v1:
1: e40fc3e5e04 ! 1: 4d9e0d7fc81 glossary: add definitions for dereference & peel
@@ Documentation/glossary-content.txt: to point at the new commit.
+<<def_object,object>> a tag points at. Tags are recursively dereferenced by +repeating the operation on the result object until the result has either a +specified <<def_object_type,object type>> (where applicable) or any non-"tag"
-+object type.
++object type. A synonym for "recursive dereference" in the context of tags is ++"<<def_peel,peel>>".
++
+Referring to a <<def_commit_object,commit object>>: the action of accessing +the commit's tree object. Commits cannot be dereferenced recursively.
@@ Documentation/glossary-content.txt: exclude;;
parents.
+[[def_peel]]peel::
-+ Synonym for object <<def_dereference,dereference>>. Most commonly used
-+ in the context of tags, where it refers to the process of recursively
-+ dereferencing a <<def_tag_object,tag object>> until the result object's
-+ <<def_object_type,type>> is something other than "tag".
++ The action of recursively <<def_dereference,dereferencing>> a
++ <<def_tag_object,tag object>>.
+
[[def_pickaxe]]pickaxe::
The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
Documentation/glossary-content.txt | 49 +++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 14 deletions(-)
Documentation/glossary-content.txt +35 -14
@@ -98,9 +98,8 @@ to point at the new commit. revision. [[def_commit-ish]]commit-ish (also committish):: - A <<def_commit_object,commit object>> or an - <<def_object,object>> that can be recursively dereferenced to - a commit object. + A <<def_commit_object,commit object>> or an <<def_object,object>> that + can be recursively <<def_dereference,dereferenced>> to a commit object. The following are all commit-ishes: a commit object, a <<def_tag_object,tag object>> that points to a commit
@@ -125,6 +124,25 @@ to point at the new commit. dangling object has no references to it from any reference or <<def_object,object>> in the <<def_repository,repository>>. +[[def_dereference]]dereference:: + Referring to a <<def_symref,symbolic ref>>: the action of accessing the + <<def_ref,reference>> pointed at by a symbolic ref. Recursive + dereferencing involves repeating the aforementioned process on the + resulting ref until a non-symbolic reference is found. ++ +Referring to a <<def_tag_object,tag object>>: the action of accessing the +<<def_object,object>> a tag points at. Tags are recursively dereferenced by +repeating the operation on the result object until the result has either a +specified <<def_object_type,object type>> (where applicable) or any non-"tag" +object type. A synonym for "recursive dereference" in the context of tags is +"<<def_peel,peel>>". ++ +Referring to a <<def_commit_object,commit object>>: the action of accessing +the commit's tree object. Commits cannot be dereferenced recursively. ++ +Unless otherwise specified, "dereferencing" as it used in the context of Git +commands or protocols is implicitly recursive. + [[def_detached_HEAD]]detached HEAD:: Normally the <<def_HEAD,HEAD>> stores the name of a <<def_branch,branch>>, and commands that operate on the
@@ -444,6 +462,10 @@ exclude;; of the logical predecessor(s) in the line of development, i.e. its parents. +[[def_peel]]peel:: + The action of recursively <<def_dereference,dereferencing>> a + <<def_tag_object,tag object>>. + [[def_pickaxe]]pickaxe:: The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore routines that help select changes that add or delete a given text
@@ -620,12 +642,11 @@ The most notable example is `HEAD`. copies of) commit objects of the contained submodules. [[def_symref]]symref:: - Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> - id itself, it is of the format 'ref: refs/some/thing' and when - referenced, it recursively dereferences to this reference. - '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic - references are manipulated with the linkgit:git-symbolic-ref[1] - command. + Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> id + itself, it is of the format 'ref: refs/some/thing' and when referenced, + it recursively <<def_dereference,dereferences>> to this reference. + '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic references + are manipulated with the linkgit:git-symbolic-ref[1] command. [[def_tag]]tag:: A <<def_ref,ref>> under `refs/tags/` namespace that points to an
@@ -661,11 +682,11 @@ The most notable example is `HEAD`. <<def_tree,tree>> is equivalent to a <<def_directory,directory>>. [[def_tree-ish]]tree-ish (also treeish):: - A <<def_tree_object,tree object>> or an <<def_object,object>> - that can be recursively dereferenced to a tree object. - Dereferencing a <<def_commit_object,commit object>> yields the - tree object corresponding to the <<def_revision,revision>>'s - top <<def_directory,directory>>. + A <<def_tree_object,tree object>> or an <<def_object,object>> that can + be recursively <<def_dereference,dereferenced>> to a tree object. + Dereferencing a <<def_commit_object,commit object>> yields the tree + object corresponding to the <<def_revision,revision>>'s top + <<def_directory,directory>>. The following are all tree-ishes: a <<def_commit-ish,commit-ish>>, a tree object,
base-commit: dadef801b365989099a9929e995589e455c51fed
Signature · 1 line
gitgitgadget
Documentation/glossary-content.txt exclude;; · line 468
Quoted 9 lines · Victoria Dye via GitGitGadget
* Removed references to "peeling" a commit; the updated definition discusses "peeling" only in the context of tags.
* Added a cross-link from "dereference" to "peel" (one already existed for "peel" to "dereference").
...
+[[def_peel]]peel::Documentation/glossary-content.txt +3
-0+ The action of recursively <<def_dereference,dereferencing>> a + <<def_tag_object,tag object>>. +
This was a bit surprising to me as I thought we would say "peel the tag once" vs "peel the tag repeatedly", but upon inspecting the existing code, documentation, and messages, we seem to mean by "to peel" to dereference a tag repeatedly until it no longer is a tag, which the new entry above exactly is (although "until the non-tag object is revealed" is missing).
Thanks. Will queue.