Honor #if when preprocessing

[bjorkstromm]

Now that https://github.com/cake-build/cake/pull/1858 is merged it would be nice if script processing also would honor defines. E.g. conditionally load files or install addins/tools.

[patriksvensson]

@mholo65 According to @devlead's integration tests, this should work ootb with the Roslyn script engine (unless I misunderstood something).

[patriksvensson]

@mholo65 Ah, I read your issue again, and I misunderstood. Sorry.

[bjorkstromm]

😄 np. Yeah, according to @devlead's testing, not even csi.exe supports it. See https://github.com/cake-build/cake/issues/1766#issuecomment-333958357

[patriksvensson]

@mholo65 This is not a trivial problem to solve unless we want to implement our own preprocessor evaluator.

#if (DEBUG && !MYTEST)  
        Console.WriteLine("DEBUG is defined");  
#elif (!DEBUG && MYTEST)  
        Console.WriteLine("MYTEST is defined");  
#elif (DEBUG && MYTEST)  
        Console.WriteLine("DEBUG and MYTEST are defined");  
#else  
        Console.WriteLine("DEBUG and MYTEST are not defined");  
#endif 

[devlead]

I rather see us implementing conditionals in the directives themselves, than doing our own compiler, while there's great reward, I feel there's great risk, with the potential of coming back to haunt us multiple times. Also the more we diverge from standards, the harder tooling will be.

[savornicesei]

Hi all,

I was redirected here from gitter, when I asked about conditionally loading an addin.

If I want to query an Oracle database from windows and linux hosts (i.e. when running integration tests) I need 2 different packages: ODP.NET Core for linux if .NET core is installed and ODP.NET for windows. Another scenario is loading different db clients based on available databases on the machine but I can live with pulling down all supported clients packages.

Thanks, Simo

[devlead]

Oracle.ManagedDataAccess.Core is .NET Standard 2.0 so should be able to work both .NET & .NET Core, if you have a recent version of .NET framework.

If you utilize Cake global tool you can use the same runtime & Cake version on all platforms and .NET Framwork won't be an factor.

That said if you really need to load different assemblies for different environments, an hacky way would be to utilize environment variables

Example this script

#addin "nuget:https://api.nuget.org/v3/index.json?package=%ORACLE_MANAGED_DATA_ACCESS_PACKAGE%"

Information(typeof(Oracle.ManagedDataAccess.Client.OracleConnection).Assembly.Location);

Calles from PowerShell

$ENV:ORACLE_MANAGED_DATA_ACCESS_PACKAGE='Oracle.ManagedDataAccess&version=18.3.0'
cake .\odpcore.cake

$ENV:ORACLE_MANAGED_DATA_ACCESS_PACKAGE='Oracle.ManagedDataAccess.Core&version=2.18.3'
cake .\odpcore.cake

Will output

+ {path to tools}\Addins\Oracle.ManagedDataAccess.18.3.0\lib\net40\Oracle.ManagedDataAccess.dll
+ {path to tools}\Addins\Oracle.ManagedDataAccess.Core.2.18.3\lib\netstandard2.0\Oracle.ManagedDataAccess.dll

Both these examples used Cake.exe so it seems Oracle.ManagedDataAccess.Core was able to be loaded on full framework, didn't try to execute anything though.

Environment variable expanding works with all preprocessor directives so if there's multiple assemblies that differ between environments an have one cake file per environment.

and do something like #load "%MY_SCRIPT_ENVVAR%"

A less magical approach would be to have something like

+ full.cake
+ core.cake
+ build.cake

have addin directives that differ in full / core and then have them load build.cake i.e.

Full

#addin "nuget:https://api.nuget.org/v3/index.json?package=Oracle.ManagedDataAccess&version=18.3.0"
#load "build.cake"

Core

#addin "nuget:https://api.nuget.org/v3/index.json?package=Oracle.ManagedDataAccess.Core&version=2.18.3"
#load "build.cake"

Build

Information(typeof(Oracle.ManagedDataAccess.Client.OracleConnection).Assembly.Location);

And have either core.cake or full.cake be the entry point depending on environment.