Pass string with expression to directive and parse in template - angularjs

Question

I'm trying to convert a string which contains an expression passed through an attribute, inside the own directive's template. The idea is to do something like this:
<div custom-directive images-source="'staticpath/blah/blah/{{Item.Src}}'"></div>
And, then inside the template, I would have a ngRepeat directive that would iterate thorugh a data set like this:
<ul>
<li ng-repeat="Item in Items">
<img ng-src="{{imagesSource}}{{Item.name}}.{{Item.extension}}" />
</li>
</ul>
The expected result should be something like this:
<ul>
<li ng-repeat="Item in Items">
<img ng-src="staticpath/blah/blah/src1/file1.jpg" />
<img ng-src="staticpath/blah/blah/src2/file2.jpg" />
<img ng-src="staticpath/blah/blah/src3/file3.jpg" />
<img ng-src="staticpath/blah/blah/src4/file4.jpg" />
</li>
</ul>
I tried to invoke $interpolate and $compile directly in my template but I get an empty string.
{{$interpolate(imagesSource)}} and {{$compile(imagesSource)}}
Any ideas?
EDIT:
Imagine the next scenario. We have a directive that will show a list of image galleries. Each image gallery will have: a title, a little description and from 1 to n images.
Ok, let's say we have a constant with the root to the images folder '/media/images/galleries/'. Then, inside the template, when on the ngRepeat loop, I will need to build the path using that constant and one of the properties (in this case we can name it 'subfolder'), but I don't want the own directive to decide which property is needed. (that's why I'd like to pass the expression in the attribute).
The directive:
<div image-galeries images-source="'staticpath/blah/blah/{{Gallery.subfolder}}'">
The template:
<div ng-repeat="Gallery in Galleries">
<h3>{{Gallery.title}}</h3>
<p>{{Gallery.description}}</p>
<ul>
<li ng-repeat="Image in Gallery.Images">
<img ng-src="{{imagesSource}}{{Image.name}}.{{Image.extension}}" />
</li>
</ul>
</div>
And the result:
<div ng-repeat="Gallery in Galleries">
<h3>Gallery 1</h3>
<p>Gallery description 1</p>
<ul>
<li ng-repeat="Image in Gallery.Images">
<img ng-src="staticpath/blah/blah/src1/file1.jpg" />
<img ng-src="staticpath/blah/blah/src1/file2.jpg" />
<img ng-src="staticpath/blah/blah/src1/file3.jpg" />
<img ng-src="staticpath/blah/blah/src1/file4.jpg" />
</li>
</ul>
</div>
<div ng-repeat="Gallery in Galleries">
<h3>Gallery 2</h3>
<p>Gallery description 2</p>
<ul>
<li ng-repeat="Image in Gallery.Images">
<img ng-src="staticpath/blah/blah/src2/file1.jpg" />
<img ng-src="staticpath/blah/blah/src2/file2.jpg" />
</li>
</ul>
</div>
Excuse me please, about my english, I hope it was clear enough :D