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Rename split-loop-with-lambda to slice-with-lambda

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The refactoring is now published as Slice on sammancoaching.org:
https://sammancoaching.org/refactorings/slice.html

- git mv ideas/split-loop-with-lambda -> ideas/slice-with-lambda
- rename learning-hour file and update frontmatter name
- update paths in tools/rehearse scripts and report title
- update prose: 'Split Loop with Lambda' -> 'Slice with Lambda'
  in learning hour, exercise READMEs, storyboard, solution comments
- link the published Slice refactoring from the pattern draft
This commit is contained in:
Your Name
2026-09-29 15:47:30 +00:00
parent 125bb7ad01
commit 77ae05c28c
114 changed files with 21 additions and 20 deletions
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ideas/slice-with-lambda/exercise/rehearsal-runs/C/agents-md.txt
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# Rehearsal workspace — refactoring task
You are refactoring `src/main/java/codingdojo/LongRangeForecasts.java` in this
Maven project. Run `mvn -q test` after each change (mvn is on your PATH). It may
fail — that is expected: the dependency on `Scorer` makes the method untestable —
but the code must still *compile*.
## Goal
In `LongRangeForecasts.longRangeForecast()`, the loop over `interestingDates`
collects weather by calling `scorer` (an unwanted external dependency).
1. Introduce a lambda for the scorer-dependent code and move its definition to
the top of the method, leaving the invocation where it is. (No refactoring
tool supports this — do it as a minimal manual edit.)
2. Extract the weather-collection loop into a new method `collectExpectedWeather`
that takes the lambda as a parameter (suggested type `LongFunction<Boolean>`).
3. Add the lambda as a parameter to `longRangeForecast` itself: the signature
must become `longRangeForecast(LongFunction<Boolean> dayOffsetToWeather)`,
with a public no-arg overload `longRangeForecast()` that delegates and wraps
the `scorer` field in a lambda. Do not keep the `String quarter` parameter.
(`java-refactor change-method-signature` or `java-refactor introduce-param`
may help; fall back to a minimal manual edit if no subcommand can do it.)
4. Stop. Report the final diff.
## Tool rules (variant C)
A semantic Java refactoring CLI, `java-refactor`, is on your PATH
(`java-refactor --help` lists the subcommands). Using it is OPTIONAL — you
may also change code with your normal file-editing tools. Choose per step
whatever you think is most reliable.
Subcommands that may be relevant for this task:
- `extract` — extract selected statements into a new private method
(selection given as start/end line+column; `--dry-run` previews)
- `introduce-param` / `change-method-signature` — alter a method's parameters
- `rename` — rename a symbol project-wide
ideas/slice-with-lambda/exercise/rehearsal-runs/C/diff.patch
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Only in /tmp/rehearsal/runs/C/workspace: AGENTS.md
diff -ru '--exclude=target' /tmp/rehearsal/pristine/src/main/java/codingdojo/LongRangeForecasts.java /tmp/rehearsal/runs/C/workspace/src/main/java/codingdojo/LongRangeForecasts.java
--- /tmp/rehearsal/pristine/src/main/java/codingdojo/LongRangeForecasts.java 2026-09-27 14:58:14.139167804 +0000
+++ /tmp/rehearsal/runs/C/workspace/src/main/java/codingdojo/LongRangeForecasts.java 2026-09-27 15:47:19.484882205 +0000
@@ -3,36 +3,26 @@
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.*;
+import java.util.function.LongFunction;
public class LongRangeForecasts {
private final Scorer scorer = new Scorer();
- public Map<IceCream, Integer> longRangeForecast(String quarter) {
+ public Map<IceCream, Integer> longRangeForecast() {
+ return longRangeForecast(daysForward -> {
+ scorer.updateSelection();
+ return scorer.lookupWeather(daysForward);
+ });
+ }
+
+ public Map<IceCream, Integer> longRangeForecast(LongFunction<Boolean> dayOffsetToWeather) {
var result = new HashMap<IceCream, Integer>();
- if (Objects.equals(quarter, "Q1") || Objects.equals(quarter, "Q4")) {
- for (IceCream flavour : IceCream.values()) {
- result.put(flavour, 5);
- }
- }
for (IceCream flavour : IceCream.values()) {
result.put(flavour, 0);
}
- List<Instant> interestingDates = List.of(
- Instant.parse("2023-05-01T14:00:00.000-07:00"),
- Instant.parse("2023-05-18T14:00:00.000-07:00"),
- Instant.parse("2023-06-05T14:00:00.000-07:00"),
- Instant.parse("2023-06-23T14:00:00.000-07:00")
- );
- List<Boolean> expectedWeather = new ArrayList<>();
- for (Instant interestingDate : interestingDates) {
- scorer.updateSelection();
- var forecastDate = Instant.parse("2023-04-26T14:00:00.000-07:00");
- long daysForward = ChronoUnit.DAYS.between(forecastDate, interestingDate);
- Boolean lookupWeather = scorer.lookupWeather(daysForward);
- expectedWeather.add(lookupWeather);
- }
+ var expectedWeather = collectExpectedWeather(dayOffsetToWeather);
for (IceCream flavour : result.keySet()) {
result.put(flavour, result.get(flavour) + 10);
@@ -46,4 +36,21 @@
}
return result;
}
+
+ private List<Boolean> collectExpectedWeather(LongFunction<Boolean> dayOffsetToWeather) {
+ List<Instant> interestingDates = List.of(
+ Instant.parse("2023-05-01T14:00:00.000-07:00"),
+ Instant.parse("2023-05-18T14:00:00.000-07:00"),
+ Instant.parse("2023-06-05T14:00:00.000-07:00"),
+ Instant.parse("2023-06-23T14:00:00.000-07:00")
+ );
+ List<Boolean> expectedWeather = new ArrayList<>();
+ for (Instant interestingDate : interestingDates) {
+ var forecastDate = Instant.parse("2023-04-26T14:00:00.000-07:00");
+ long daysForward = ChronoUnit.DAYS.between(forecastDate, interestingDate);
+ Boolean lookupWeather = dayOffsetToWeather.apply(daysForward);
+ expectedWeather.add(lookupWeather);
+ }
+ return expectedWeather;
+ }
}
diff -ru '--exclude=target' /tmp/rehearsal/pristine/src/test/java/codingdojo/DailyForecastsTest.salesForecast.received.txt /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/DailyForecastsTest.salesForecast.received.txt
--- /tmp/rehearsal/pristine/src/test/java/codingdojo/DailyForecastsTest.salesForecast.received.txt 2026-09-27 14:58:16.443126144 +0000
+++ /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/DailyForecastsTest.salesForecast.received.txt 2026-09-27 15:47:22.446807369 +0000
@@ -1,4 +1,4 @@
Forecast at: 2026-09-27
Steve score: 9
-Julie score: 9
+Julie score: 3
Francis score: 3
diff -ru '--exclude=target' /tmp/rehearsal/pristine/src/test/java/codingdojo/LongRangeForecastsTest.java /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/LongRangeForecastsTest.java
--- /tmp/rehearsal/pristine/src/test/java/codingdojo/LongRangeForecastsTest.java 2026-09-27 14:58:14.139167804 +0000
+++ /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/LongRangeForecastsTest.java 2026-09-27 15:47:19.484882205 +0000
@@ -13,8 +13,7 @@
@Test
void longRangeForecast() {
- var quarter = "Q3";
- var actual = new LongRangeForecasts().longRangeForecast(quarter);
+ var actual = new LongRangeForecasts().longRangeForecast();
StringBuilder printedResult = printIceCreamForecast(actual);
Approvals.verify(printedResult);
diff -ru '--exclude=target' /tmp/rehearsal/pristine/src/test/java/codingdojo/LongRangeForecastsTest.longRangeForecast.received.txt /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/LongRangeForecastsTest.longRangeForecast.received.txt
--- /tmp/rehearsal/pristine/src/test/java/codingdojo/LongRangeForecastsTest.longRangeForecast.received.txt 2026-09-27 14:58:16.402126886 +0000
+++ /tmp/rehearsal/runs/C/workspace/src/test/java/codingdojo/LongRangeForecastsTest.longRangeForecast.received.txt 2026-09-27 15:47:22.405808404 +0000
@@ -1 +1 @@
-{Strawberry:10, Chocolate:10, Vanilla:10, }
\ No newline at end of file
+{Strawberry:12, Chocolate:12, Vanilla:12, }
\ No newline at end of file
ideas/slice-with-lambda/exercise/rehearsal-runs/C/measure.txt
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--- Run C ---
session file: /tmp/rehearsal/runs/C/session/2026-09-27T15-45-09-782Z_01a0e38a-a696-7513-8cb3-d7e75370aeff.jsonl
model: z-ai/glm-5.3-flash
session span: 156.5 s
assistant messages: 20
tool calls: 23 total
bash 15
read 4
edit 4
tokens input: 13250
tokens output: 8393
tokens cacheRead: 124544
tokens cacheWrite: 0
tokens reasoning: 4618
tokens TOTAL (sum): 150805
--- /usr/bin/time -v (wall clock + max RSS) ---
Elapsed (wall clock) time (h:mm:ss or m:ss): 2:36.61
Maximum resident set size (kbytes): 248952
Exit status: 0
--- pi stdout (last 15 lines) ---
+ }
+ return expectedWeather;
+ }
}
```
Supporting change in `src/test/java/codingdojo/LongRangeForecastsTest.java`:
```diff
- var quarter = "Q3";
- var actual = new LongRangeForecasts().longRangeForecast(quarter);
+ var actual = new LongRangeForecasts().longRangeForecast();
```
Stopping here as instructed.
ideas/slice-with-lambda/exercise/rehearsal-runs/C/pi-stdout.txt
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All four steps are complete. Here's the summary:
## What was done
1. **Lambda introduced** (manual edit): the `scorer.updateSelection()` + `scorer.lookupWeather(...)` code became a `LongFunction<Boolean> dayOffsetToWeather` lambda defined at the top of the method; the loop now calls `dayOffsetToWeather.apply(daysForward)`.
2. **Extracted** the weather-collection loop with `java-refactor extract` (the tool generated `collectExpectedWeather(interestingDates, dayOffsetToWeather, expectedWeather)`), then a minimal manual cleanup gave it the suggested shape `private List<Boolean> collectExpectedWeather(LongFunction<Boolean> dayOffsetToWeather)` returning the list.
3. **Signature changed** (manual edit — neither `change-method-signature` nor `introduce-param` supports removing the `quarter` parameter): now `public Map<IceCream, Integer> longRangeForecast(LongFunction<Boolean> dayOffsetToWeather)` plus a public no-arg overload delegating with a lambda wrapping the `scorer` field. The `quarter` branch was dropped (it was inert anyway — its `put(flavour, 5)` was immediately overwritten by `put(flavour, 0)`), and the test call site updated to `longRangeForecast()`.
4. `mvn -q test` was run after every change: code compiles throughout; the 2 remaining failures (`LongRangeForecastsTest`, `DailyForecastsTest`) are the expected pre-existing ones caused by the `Scorer` state dependency.
## Final diff — `src/main/java/codingdojo/LongRangeForecasts.java`
```diff
@@ -3,36 +3,26 @@
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.*;
+import java.util.function.LongFunction;
public class LongRangeForecasts {
private final Scorer scorer = new Scorer();
- public Map<IceCream, Integer> longRangeForecast(String quarter) {
+ public Map<IceCream, Integer> longRangeForecast() {
+ return longRangeForecast(daysForward -> {
+ scorer.updateSelection();
+ return scorer.lookupWeather(daysForward);
+ });
+ }
+
+ public Map<IceCream, Integer> longRangeForecast(LongFunction<Boolean> dayOffsetToWeather) {
var result = new HashMap<IceCream, Integer>();
- if (Objects.equals(quarter, "Q1") || Objects.equals(quarter, "Q4")) {
- for (IceCream flavour : IceCream.values()) {
- result.put(flavour, 5);
- }
- }
for (IceCream flavour : IceCream.values()) {
result.put(flavour, 0);
}
- List<Instant> interestingDates = List.of(
- Instant.parse("2023-05-01T14:00:00.000-07:00"),
- Instant.parse("2023-05-18T14:00:00.000-07:00"),
- Instant.parse("2023-06-05T14:00:00.000-07:00"),
- Instant.parse("2023-06-23T14:00:00.000-07:00")
- );
- List<Boolean> expectedWeather = new ArrayList<>();
- for (Instant interestingDate : interestingDates) {
- scorer.updateSelection();
- var forecastDate = Instant.parse("2023-04-26T14:00:00.000-07:00");
- long daysForward = ChronoUnit.DAYS.between(forecastDate, interestingDate);
- Boolean lookupWeather = scorer.lookupWeather(daysForward);
- expectedWeather.add(lookupWeather);
- }
+ var expectedWeather = collectExpectedWeather(dayOffsetToWeather);
for (IceCream flavour : result.keySet()) {
result.put(flavour, result.get(flavour) + 10);
@@ -46,4 +36,21 @@
}
return result;
}
+
+ private List<Boolean> collectExpectedWeather(LongFunction<Boolean> dayOffsetToWeather) {
+ List<Instant> interestingDates = List.of(
+ Instant.parse("2023-05-01T14:00:00.000-07:00"),
+ Instant.parse("2023-05-18T14:00:00.000-07:00"),
+ Instant.parse("2023-06-05T14:00:00.000-07:00"),
+ Instant.parse("2023-06-23T14:00:00.000-07:00")
+ );
+ List<Boolean> expectedWeather = new ArrayList<>();
+ for (Instant interestingDate : interestingDates) {
+ var forecastDate = Instant.parse("2023-04-26T14:00:00.000-07:00");
+ long daysForward = ChronoUnit.DAYS.between(forecastDate, interestingDate);
+ Boolean lookupWeather = dayOffsetToWeather.apply(daysForward);
+ expectedWeather.add(lookupWeather);
+ }
+ return expectedWeather;
+ }
}
```
Supporting change in `src/test/java/codingdojo/LongRangeForecastsTest.java`:
```diff
- var quarter = "Q3";
- var actual = new LongRangeForecasts().longRangeForecast(quarter);
+ var actual = new LongRangeForecasts().longRangeForecast();
```
Stopping here as instructed.
ideas/slice-with-lambda/exercise/rehearsal-runs/C/prompt.txt
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Read AGENTS.md in this directory and execute the refactoring task it describes. Run mvn -q test after each change. When done, stop and report the final diff of LongRangeForecasts.java.
ideas/slice-with-lambda/exercise/rehearsal-runs/C/time.txt
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@@ -0,0 +1,23 @@
Command being timed: "timeout -k 15 600 pi -p -a --session-dir /tmp/rehearsal/runs/C/session --name rehearsal-C Read AGENTS.md in this directory and execute the refactoring task it describes. Run mvn -q test after each change. When done, stop and report the final diff of LongRangeForecasts.java."
User time (seconds): 31.11
System time (seconds): 2.42
Percent of CPU this job got: 21%
Elapsed (wall clock) time (h:mm:ss or m:ss): 2:36.61
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 248952
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 713860
Voluntary context switches: 71439
Involuntary context switches: 2116
Swaps: 0
File system inputs: 0
File system outputs: 3240
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0
ideas/slice-with-lambda/exercise/rehearsal-runs/C/verify.txt
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@@ -0,0 +1,10 @@
--- Run C ---
final diff vs pristine: 52 changed lines -> /tmp/rehearsal/runs/C/diff.patch
mvn test with solution's test + approved file:
RESULT: PASS (deterministic)
structural checks:
[x] method collectExpectedWeather exists
[x] takes LongFunction<Boolean> parameter
[i] note: 'scorer' still referenced in LongRangeForecasts.java
[x] lambda syntax present
[i] main class differs from reference solution (may still be a valid variant)