p.s. The package supplies a `define-struct-updaters` macro separately.
This is handy because you can use it on any structs -- including those
from other modules you don't control. If you do this frequently for
your own structs, you could of course write a little macro to `(begin
(struct id ) (d
On Thu, Dec 7, 2017 at 11:08 AM, David Storrs wrote:
> assembled. There's no reason not to use functional update, but I
> haven't seen a straightforward way to do that since there is no
> 'set-db-chunk-foo' as opposed to 'set-db-chunk-foo!'. I guess I need
> to use 'struct-copy'? At that point
I'm not sure whether the following is a good idea, but it more or less
works. The impersonate-struct function allows one to redirect the some
or all of accessor and mutator functions on *individual struct
instances*. If the actual constructor is hidden from the user and only
a ``smart'' constructor
Wow. Thank you, Matthias. That's impressive.
On Thu, Dec 7, 2017 at 10:46 AM, Matthias Felleisen
wrote:
>
> On Dec 6, 2017, at 10:45 PM, David Storrs wrote:
>
> I have a struct that looks like this (simplified for concision):
>
> (struct db-chunk (scratchdir-path chunkdir-path) #:mutable)
>
>
On Wed, Dec 6, 2017 at 11:23 PM, Philip McGrath
wrote:
>
>> 1) At least one of the fields must be set at creation
>
>
> What does it mean for one of the fields not to be set at creation? Is there
> implicitly some not-initialized value like #f that is also valid for the
> constructor? Do you want
> On Dec 6, 2017, at 10:45 PM, David Storrs wrote:
>
> I have a struct that looks like this (simplified for concision):
>
> (struct db-chunk (scratchdir-path chunkdir-path) #:mutable)
>
> I'd like to ensure that:
>
> 1) At least one of the fields must be set at creation
> 2) Both fields will
> 1) At least one of the fields must be set at creation
>
What does it mean for one of the fields not to be set at creation? Is there
implicitly some not-initialized value like #f that is also valid for the
constructor? Do you want your accessor functions to raise an error if
someone tries to acce
I have a struct that looks like this (simplified for concision):
(struct db-chunk (scratchdir-path chunkdir-path) #:mutable)
I'd like to ensure that:
1) At least one of the fields must be set at creation
2) Both fields will accept only a path-string? value
3) Both fields will return string? when
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