Vue - Bug or design with template vslots - vue.js

Question

I notice that some of my computed properties don't fire when they call upon the same data. As a super-simplistic example let's say I have this:
<template v-for="item in foo" v-slot:['sameSlot`]="{sameBlah}">
{{ JSON.stringify(item) }}
</template>
<template v-for="item in bar" v-slot:['sameSlot`]="{sameBlah}">
{{ JSON.stringify(item) }}
</template>
<template v-for="item in baz" v-slot:['sameSlot`]="{sameBlah}">
{{ JSON.stringify(item) }}
</template>
...
data: () => ({
someData: [
{type:'foo', value: 1},
{type:'bar', value: 2},
{type:'baz', value: 3},
],
});
computed: {
foo() {
console.log('Hello from foo');
return this.someData.filter(f => f.type === 'foo');
},
bar() {
console.log('Hello from bar');
return this.someData.filter(f => f.type === 'bar');
},
baz() {
console.log('Hello from baz');
return this.someData.filter(f => f.type === 'baz');
},
}
If I run that, I only see console output from one of the computed methods, not all. Same with seeing results in the templates. Is this by design?
BTW I'm aware I could eliminate the computed properties by creating a method where a filter key could be passed in, but that doesn't showcase this 'issue'.

Answer 1

The code in the post targets the same slot 3 times, so Vue completely ignores the first 2 without running any of the code in the first two templates even once.
This is a smart feature to minimize workload because it's not sensible to target the same slot more than once to begin with. If anything, maybe there should be a warning from the compiler in this situation.
You could even have code that tries to use variables which don't exist, and there will be no compiler warning. For example:
<!-- First call: completely ignored, no error -->
<template v-for="item in notDefinedOnTheInstance" v-slot:[`sameSlot`]="{sameBlah}">
{{ JSON.stringify(item) }}
</template>
<!-- Second call: used for the slot -->
<template v-for="item in baz" v-slot:[`sameSlot`]="{sameBlah}">
{{ JSON.stringify(item) }}
</template>
Despite not existing in the instance, notDefinedOnTheInstance won't throw a warning because that whole section has been ignored. So it's for this reason that you also don't see the computeds output in the console, because they never run.