Here are my thoughts on the three approaches: Approach #1: This seems the most straightforward. I'd write a function that takes a map of conditions, and returns a list of tuples. You can then do what you want with the list of tuples.
Approach #2: Remember the first rule of macro club: Don't write macros if a function will do. From what you've described, this application wraps a simple SELECT * FROM... , and a macro is overkill. Approach #3: This is a good approach once you hit the limits of the first approach, and before you move on to the second approach. I've written SQL apps in Clojure too. And I've used approaches 1 and 3. I only use approach 2 when I really have to, and I try to have the macro do as little as possible. In summary, try approaches: 1 -> 3 -> 2 I'll try to throw some code on github this evening so you can see an example of what I do, and you can decide if it's a good fit for your application. Sean On May 11, 4:05 am, Janico Greifenberg <jgre...@googlemail.com> wrote: > Hi, > > I'm writing an RSS-reader using compojure and clojure.contrib.sql. As > this is my first project in a functional language, I'm not sure about > how to design the application. The concrete question I'm having right > now, is how to encapsulate database queries in functions. For my > RSS-reader, a basic operations is to display lists of feeds that I > retrieve with the following code: > > (sql/with-connection db > (sql/with-query-results > feeds > ["select id, title from feeds order by title"] > > As this happens at a few places in the code, I would like to > encapsulate it somehow. I see several approaches to this, but I'm > uncertain which of them is the most idiomatic way to do this in > Clojure. > > (1) The straightforward approach seems to be a function that returns > the feeds. However, I would have to call (doall feeds) to get the data > out of the internals of contrib.sql/JDBC and into my application. So I > guess this would not be the most efficient way. > > (2) Another idea is to create a function or macro with-feeds that > wraps the query and creates a binding to be used inside the body. > > (3) Or I could have a function that takes another function as a > parameter which gets called inside with-query-results and gets feeds > as parameter. > > Which of these variants -- or another one that I did not think of -- > would you recommend? > > Janico --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
