[Protium] Templating

Finally, after much talk, here's some action on the Protium front. This the first posting in the 'Isotopes of Hydrogen' series, on the subject of Templating. IoH is housed at the Protium Blue Forum.

If you don't want to go through the process of forum registration, the article is reproduced below.

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We're implementing a SOAP interface to Google's AdWords. There are a number of services and subroutines. The following code was developed to speed up the implementation by taking the service and subroutines names and turning them into VB6 subs.

<@ LETVARLIT>template| Sub &Function;(oEnvelope As CoEnvelope, _ oHTTP As HTTPTransport, _ URL As String, _ URI As String, _ Method As String, _ sService As String, _ sMethod As String, _ dDate As Date) Method = "&Function;" URI = ADWORDS_API URL = &Service; oEnvelope.SetMethod Method, URI oEnvelope.Parameters.Create "service", sService oEnvelope.Parameters.Create "method", sMethod oEnvelope.Parameters.Create "date", dDate oHTTP.SOAPAction = Method End Sub</@>

First there's the definition of template. Note that some parts of the template are Visual BASIC and some are something else: an ampersand, a word and a semicolon. These will be replaced with the text in the following list.

<@ LETVARLIT>params|TRAFFIC_ESTIMATOR_SERVICE checkKeywordTraffic estimateAdGroupList estimateCampaignList estimateKeywordList</@>

params contains, as a first item, the name of the service. After it are all the routines germane to that service. I got these by copying and pasting from Google's AdWords API website.

<@ LETCNDLSTVARLIT>L|params| </@>

This bit takes the variable params, and converts it to a list, splitting on newlines. CND means 'construct delimited'. The list is called L (really original, I know.)

<@ ITEENULSTLIT>L| <@ INILIT> <@ DEFMACELTLST>Service|L</@> </@> <@ ONGLIT> <@ DEFMACELTLST>Function|L</@> <@ SAYEKMVAR>template</@> </@> </@>

Next we iterate by enumeration of the L list. Here we see one of the special qualifiers that can be used with iteration, INI, that only fires on the first pass through the iteration and is ignored otherwise. In this case, its 'payload' is to define a macro where Service contains the current (in this case, the first) element of the L list.

ONG means 'ongoing' and fires on the second and subsequent iterations. The payload is in two parts. The first is to define another macro, Function, with the value of the current element of L. The second is to evaluate template, using EKM, substituting &Service; and &Function; with the values stored in the Service and Function macros.

By using INI, Service gets set only once. ONG ensures that Function will never contain the name of the service, and always contain the current name of the function.

An abbreviated sample of the output is below. There are 11 services and over 40 subs in total. Granted, there's still quite a bit of work to make these subs useful, but a lot of the hack work has been done by the computer, which is what it's there for.

Sub checkKeywordTraffic(oEnvelope As CoEnvelope, _ oHTTP As HTTPTransport, _ URL As String, _ URI As String, _ Method As String, _ sService As String, _ sMethod As String, _ dDate As Date) Method = "checkKeywordTraffic" URI = ADWORDS_API URL = TRAFFIC_ESTIMATOR_SERVICE oEnvelope.SetMethod Method, URI oEnvelope.Parameters.Create "service", sService oEnvelope.Parameters.Create "method", sMethod oEnvelope.Parameters.Create "date", dDate oHTTP.SOAPAction = Method End Sub ... Sub estimateKeywordList(oEnvelope As CoEnvelope, _ oHTTP As HTTPTransport, _ URL As String, _ URI As String, _ Method As String, _ sService As String, _ sMethod As String, _ dDate As Date) Method = "estimateKeywordList" URI = ADWORDS_API URL = TRAFFIC_ESTIMATOR_SERVICE oEnvelope.SetMethod Method, URI oEnvelope.Parameters.Create "service", sService oEnvelope.Parameters.Create "method", sMethod oEnvelope.Parameters.Create "date", dDate oHTTP.SOAPAction = Method End Sub

© Copyright Bruce M. Axtens, 2007