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Why there is no #define before PLUGINLIB_EXPORT_CLASS macro?

asked 2020-08-28 21:38:48 -0500

RicoJ
41 ●10 ●12 ●19 https://ricojia.github.io/

updated 2020-08-29 01:00:33 -0500

gvdhoorn
86574 ●283 ●1432 ●1054 http://cor.tudelft.nl/

When we want to make a plugin, we need to register the plugin

PLUGINLIB_EXPORT_CLASS(carrot_planner::CarrotPlanner, nav_core::BaseGlobalPlanner)

My understanding is that this is the redefinition of the pluginlib_export_class macro. However, from what I have seen so far, we need #define for this. How come there is no #define?

Thanks, Rico

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answered 2020-08-29 01:01:54 -0500

gvdhoorn
86574 ●283 ●1432 ●1054 http://cor.tudelft.nl/

updated 2020-08-29 03:27:26 -0500

My understanding is that this is the redefinition of the pluginlib_export_class macro.

Not quite: it's an invocation of the macro.

However, from what I have seen so far, we need #define for this. How come there is no #define?

Because you're not defining a macro, but invoking it.

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Good point, but note that there is no semicolon ; after the macro. My understanding is that when we invoke a macro, there is always a ;. Here is an example for a macro with no semicolon

This is interesting