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Clean up makeGraph.makeGetter #1167

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Clean up makeGraph.makeGetter #1167

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34 changes: 16 additions & 18 deletions src/util/makeGraph.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,26 +12,24 @@ function makeGetter<GraphType, K extends keyof GraphType>(
key: K,
): () => GraphType[K] {
return () => {
let returnValue: GraphType[K];

if (components[key] == null) {
if (lockedKeys.includes(key)) {
const cycle = [...lockedKeys.slice(lockedKeys.indexOf(key)), key].join(
" -> ",
);
throw new Error(`Dependency injection graph cycle detected: ${cycle}`);
}
const factory = factoryMap[key] as (graph: GraphType) => GraphType[K];
lockedKeys.push(key);
returnValue = factory(graph);
if (lockedKeys.pop() !== key) {
throw new Error("Unexpected key at top of graph stack");
}
components[key] = returnValue;
} else {
returnValue = components[key] as GraphType[K];
const componentValue = components[key];
if (componentValue != null) {
return componentValue;
Comment on lines +15 to +17
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If TypeScript is updated we should be able to still check components[key] without an intermediate const: https://devblogs.microsoft.com/typescript/announcing-typescript-4-7/#control-flow-analysis-for-element-access

Suggested change
const componentValue = components[key];
if (componentValue != null) {
return componentValue;
if (components[key] != null) {
return components[key];

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Nice. Fwiw I'll prob just close this PR tho. I factored it out of another PR, but we're moving to pure DI, so this code is all going to go away

}

if (lockedKeys.includes(key)) {
const cycle = [...lockedKeys.slice(lockedKeys.indexOf(key)), key].join(
" -> ",
);
throw new Error(`Dependency injection graph cycle detected: ${cycle}`);
}
const factory = factoryMap[key];
lockedKeys.push(key);
const returnValue = factory(graph);
if (lockedKeys.pop() !== key)˜ {
throw new Error("Unexpected key at top of graph stack");
}
components[key] = returnValue;
return returnValue;
};
}
Expand Down