How to assemble a topcell with height-fixed-yet-width-varying modules using skill code?

My first post in this community. I am very new to skill code. Thank you for helping out in advance.

For each tapeout, I need to place all the modules together into a topcell. These modules have fixed height (determined by padframe), but varying widths depending on contents. The modules origins always locate at the bottom left corner.

To build the topcell, these modules are placed in horizontal way, back to back, that is, the newly-added module is placed next to the very edge of the early placed ones. I draw a schematic below to illustrate this.

From programing perspective, it is quite straightforward (similar to a For loop) as I also show below, but my difficulty is how to convert the idea into skill code, which I know little.

Such skill code is probably one of the most common scripts that layout eng uses every day, yet, for a rookie like me, it (e.g. syntax and coding) still looks overwhleming to me. I bet I can read your script but can't write it myself :). 

Can any body educate me how to implement such skill code? A general code framework or existing examples/articles would be appreciated? Thank you so much.