Alpha Tech: Xdialog & Collections

[Jamin Dunivan]

Is there a way to use collections in Xdialog. I know you can use arrays like var[1]. I am used to them being called hashes and in PERL the way you refered to them was var{key}. Is there or will there be a way of doing this?

Thanks
Jamin

[Selwyn Rabins]

RE: Alpha Tech: Xdialog & Collections

i am not sure what you want to do with the collection, but assuming you have a collection, and you want to display a list box with the data in the collection, then you would first have to dump the data from the collection into a crlf delimited string (the collection object supports a method to dump out it contents), then then use the resulting crlf string in your xdialog.



in general, i like property arrays better than collections because there is a lot more power associated with property arrays.

[Jamin Dunivan]

RE: Alpha Tech: Xdialog & Collections

With collections you do not need to know the order of the fields in a table because it is determined by key not sequential order.

I have a vendor table I want to display a quick pop up window with info of that vendors record. I can put all the values into a collection and access them by key without having to know the order of the fields.

Jamin

[JerryBrightbill]

RE: Alpha Tech: Xdialog & Collections

Jamin

I also like using collections since I can use a key value to find a value in the collection and I don't need to determine ahead of time how many records will be in the collection. Converting to crlf delimited list is simple for use in an xdialog using mycollection.dump("value"). See page 63 of the xbasic manual.

Jerry

[Selwyn Rabins]

RE: Alpha Tech: Xdialog & Collections

it is true that you can use a key to find a value in a collection. that's nice.

however, property arrays have these benefits:

1. a collection is essentially a two column table. key is column 1 and data is column 2. --- a property array is a table with unlimited number of columns.

2. you can find a value in a property array by key.
for example, say that you have this property array:

dim a[10] as p
a[1].name = "jerry"
a[1].city = "london"
a[2].name = "selwyn"
a[2].city = "boston"


now, say i want to find the city for "jerry"

indx = a.find("jerry","name")
?a[indx].city


in practice, i would make the array search case and length insensitive, and i would protect for no match.

indx = a.find(ut("jerry"),"ut(name)")
if index > 0 then
city = a[indx].city
else
city = "Not found"
end if

[Lenny Forziati]

RE: Alpha Tech: Xdialog & Collections

Jamin,

Coming from a Perl and PHP background myself, I was a bit confused with Xbasic arrays at first and thought I was limited in what I could do. But after some time with Xbasic, I think it is actually easier to work with. Here are a couple of options for you.

1) Dot variables - With this arrangement you would have something like:

dim data as p
data.firstname = "Lenny"
data.lastname = "Forziati"
data.phone_number = "781-229-4500"

It sounds like this would meet your needs for what you are trying to do. This essentially gives you keys for each piece of data which elminates the need to track field order.

2) Pointer array - Store multiple records with something like:

dim data[2] as p
data[1].firstname = "Jamin"
data[1].lastname = "Dunivan"
data[2].firstname = "Lenny"
data[2].lastname = "Forziati"

Xbasic will do what you need, it just does it a bit differently than Perl.

-Lenny

[Jamin Dunivan]

RE: Alpha Tech: Xdialog & Collections

In PERL you can have hashes of hashes(hash=collection), hashes of arrays, arrays of hashes and arrays of arrays. This is very powerful functionality that I am used to. I was delighted to see that you added collections but I guess I kind of compared it to PERL without actually digging into it.

I will study your examples. Thank You!
Jamin

[Jamin Dunivan]

RE: Alpha Tech: Xdialog & Collections

Thanks Lenny!

It helps to hear from somone who knows where I am!

Jamin

[JerryBrightbill]

RE: Alpha Tech: Xdialog & Collections

Collections and dot variable arrays each have advantages depending on what you are doing. Collections work real well if you only need a key value and a single return value. For instance, state abbreviations and state names, or a product code and product description. Dot.variable arrays are nice if each array entry has more that one associated value as in Selwyn's example. The variable a[1] has name and city or more. I have found uses for both.

Like many things in Alpha, there is more than one way to get similar results. You just have to fit the method to the need.

Jerry

[Selwyn Rabins]

RE: Alpha Tech: Xdialog & Collections

without knowing perl, i suspect that there is equivalent functionality in a5.

a5's property arrays are incredibly powerful because you can have an unlimited number of nested arrays (which sounds a little like what you are talking about.

consider this.

dim a[3] as p
a[1].name = "fred"
dim a[1].kids[3] as p
a[1].kids[1].name = "sam"
a[1].kids[1].age = 9
a[1].kids[2].name = "john"
a[1].kids[2].age = 3
a[1].city = "boston"

in this case a[1] has 3 properties: name-- a char variable, kids -- a property array (i.e. a nested array) and age -- a numeric variable.

then, the icing on the cake is a5's property_to_string() function which allows you to dump out a complex variable (such as 'a' in this case) to a string, so that you can save the contents of your array and then later reinitialize it.

[JerryBrightbill]

RE: Alpha Tech: Xdialog & Collections

What? Wow! And I am just getting the hang of simple dot variables. I never knew about nested arrays. Got to back to the manual....

Jerry