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Do I always have to declare parameters?

ros2

asked 2019-06-17 02:45:13 -0500

xhuan28
31 ●5 ●10 ●15

declare_parameter() is a new API in dashing release. Per my understanding from parameter demos,

// Declare parameters that may be set on this node
node->declare_parameter("bar");
node->declare_parameter("foo");

we have to declare a parameter if we want to set this parameter in a node. But when I develop a node in which only get_parameter() function is invoked, but it seems that I still need to declare_parameter(). Do I always have to declare parameters whatever get or set parameters?

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answered 2019-06-17 11:33:32 -0500

sloretz
3061 ●25 ●86 ●55

By default yes you must declare parameters, but there is an option to opt out. To opt out, set allow_undeclared_parameters to true. Here is an example.

In many cases you know all the parameters that your node can use. In these cases you should use the default behavior and declare your parameters.