From: Richard W.M. Jones <rjones@redhat.com>
Date: Thu, 20 Feb 2020 11:21:36 +0000 (+0000)
Subject: Updated goals talk for tech talk.
X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=3684e2f574200b0940ed38e057522e538e52edfa;p=libguestfs-talks.git

Updated goals talk for tech talk.

Tactics -> predicates.

Mention other todo items.

Other cleanups.
---

diff --git a/2020-goals/2020-goals.odp b/2020-goals/2020-goals.odp
index 5e73701..6945c11 100644
Binary files a/2020-goals/2020-goals.odp and b/2020-goals/2020-goals.odp differ
diff --git a/2020-goals/notes.txt b/2020-goals/notes.txt
index fa186eb..f5757bd 100644
--- a/2020-goals/notes.txt
+++ b/2020-goals/notes.txt
@@ -16,15 +16,15 @@ we addressed some shortcomings.
 
 
 
-TACTIC PROBLEM:
+PREDICATE PROBLEM:
 
-Only one tactic for solving dependencies.
+Only one predicate for solving dependencies.
 
 "If the target file doesn't exist, or if it's older than
 one of the dependencies, then run this recipe."
 
 If you think for a little while you'll see that other
-tactics are possible:
+predicates are possible:
 
      eg: URL, newer than any file (not all files),
          Koji build, comparing checksums, test with skip
@@ -125,26 +125,26 @@ if you want you can also run compile ("bar") directly:
 
 
 
-Tactics are special rules that we can use to change how we
+Predicates are special rules that we can use to change how we
 determine if a goal needs to be rebuilt.  When you see a
-filename string, there's an implicit tactic called *file, so
+filename string, there's an implicit predicate called is-file, so
 these are equivalent, because when goals sees a bare string
-but it wants a tactic it implicitly uses *file.
+but it wants a predicate it implicitly uses is-file.
 
   "target" : "foo.o", "bar.o" { ... }
 
-  *file("target") : *file("foo.o"), *file("bar.o") { ... }
+  is-file("target") : is-file("foo.o"), is-file("bar.o") { ... }
 
 
-Apart from *file being the default tactic, it's not built
-into goals.  In fact *file is defined in the goals standard
+Apart from is-file being the default predicate, it's not built
+into goals.  In fact is-file is defined in the goals standard
 library.  The special @{...} code section means the code
 doesn't print verbosely when its running.  And "exit 99"
-is used by the tactic to indicate that the target needs
+is used by the predicate to indicate that the target needs
 to be rebuilt, but other than that it's all written in
 ordinary shell script:
 
-  tactic *file (filename) = @{
+  predicate is-file (filename) = @{
       test -f %filename || exit 99
       for f in %<; do
           test %filename -ot "$f" && exit 99 ||:
@@ -153,11 +153,11 @@ ordinary shell script:
 
 
 
-And you can of course write other tactics in shell script.
-Here's a tactic for running test suites.  This tactic lets
+And you can of course write other predicates in shell script.
+Here's a predicate for running test suites.  This predicate lets
 you skip a test by setting an environment variable.
 
-     tactic *test (script) = @{
+     predicate is-test (script) = @{
          # Check if SKIP variable is set.
          skip_var=$(
              echo -n SKIP_%script |
@@ -168,19 +168,19 @@ you skip a test by setting an environment variable.
          if test %goals_final_check; then exit 0; else exit 99; fi
      }
 
-You can use the tactic like this.  There's quite a lot to unpack
+You can use the predicate like this.  There's quite a lot to unpack
 in this example, but I'll just say that the wildcard function
 expands to a list of files, and the wrap function changes them
-from a list of strings into a list of *test tactics.
+from a list of strings into a list of is-test predicates.
 
-    let tests = wrap ("*test", wildcard ("test-*.sh"))
+    let tests = wrap ("is-test", wildcard ("test-*.sh"))
     goal check () = : tests
-    goal run (script) = *test(script) : { ./%script }
+    goal run (script) = is-test(script) : { ./%script }
 
 
-Another tactic we use is called *koji-built, which I
+Another predicate we use is called is-koji-built, which I
 use for mass rebuilding Fedora packages in dependency order.
-I won't go into the full definition of *koji-built since
+I won't go into the full definition of is-koji-built since
 interfacing with Koji is quite complicated, but you can
 write a mass rebuild tool in goals fairly easily:
 
@@ -232,10 +232,10 @@ because they point to future ways we might explore this space.
     goal link = "program" : "foo.o" { %CC %CFLAGS %< -o %@ }
 
 
- - Tactics are constructors
+ - Predicates are constructors
  - Targets are patterns
 
-    *file ("%name.o") : ...     match name with
+    is-file ("%name.o") : ...   match name with
                                 | File (name + ".o") -> compile name
                                 | ...
 
@@ -280,16 +280,13 @@ TO-DO
 ----
 to do:
 
- - Explain tactics better, Kashyap found it confusing.
-
- - Should "tactic" be "predicate"?
-   Tactics might use ‘is-’ instead of ‘*’, eg. is-file, is-koji-built
+ - Explain predicates better, Kashyap found it confusing.
 
  - Cover some of the other tools that are better makes.
    (Note I'm not covering all DAG solvers like Ninja unless they
    bring something new to the table)
 
-   * Plan 9 mk - has alternate build tactics
+   * Plan 9 mk - has alternate build predicates
 
    * https://github.com/casey/just - has functions and multi-parameter rules