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<title>Questions & Answers</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.75.2"><link rel="home" href="index.html" title="Meta State Machine (MSM)"><link rel="up" href="index.html" title="Meta State Machine (MSM)"><link rel="prev" href="ar01s05.html" title="Performance / Compilers"><link rel="next" href="ar01s07.html" title="Internals"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Questions & Answers</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s05.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ar01s07.html">Next</a></td></tr></table><hr></div><div class="sect1" title="Questions & Answers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e3798"></a>Questions & Answers</h2></div></div></div><p><span class="underline">Question</span>: on_entry gets as argument, the sent
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event. What event do I get when the state becomes default-activated (because it is an
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initial state)?</p><p>
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<span class="underline">Answer</span>: To allow you to know that the state was
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default-activated, MSM generates a boost::msm::InitEvent default event. </p><p><span class="underline">Question</span>: Why do I see no call to no_transition
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in my composite state? </p><p><span class="underline">Answer</span>: Because of the priority rule defined by
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UML. It says that in case of transition conflict, the most inner state has a higher
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priority. So after asking the inner state, the containing composite has to be also asked
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to handle the transition and could find a possible transition.</p><p><span class="underline">Question</span>: Why do I get a compile error saying
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the compiler cannot convert to a function ...Fsm::*(some_event)? </p><p><span class="underline">Answer</span>: You probably defined a transition
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triggered by the event some_event, but used a guard/action method taking another event. </p><p><span class="underline">Question</span>: Why do I get a compile error saying
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something like “too few” or “too many” template arguments? </p><p><span class="underline">Answer</span>: You probably defined a transition in
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form of a a_row or g_row where you wanted just a _row or the other way around. With Row,
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it could mean that you forgot a "none". </p><p><span class="underline">Question</span>: Why do I get a very long compile error
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when I define more than 20 rows in the transition table? </p><p><span class="underline">Answer</span>: MSM uses Boost.MPL under the hood and
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this is the default maximum size. Please define the following 3 macros before including
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any MSM headers: </p><p><code class="code">#define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS </code></p><p><code class="code">#define BOOST_MPL_LIMIT_VECTOR_SIZE 30 // or whatever you need </code></p><p><code class="code">#define BOOST_MPL_LIMIT_MAP_SIZE 30 // or whatever you need </code></p><p><span class="underline">Question</span>: Why do I get this error: ”error C2977:
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'boost::mpl::vector' : too many template arguments”? </p><p><span class="underline">Answer</span>: The first possibility is that you
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defined a transition table as, say, vector17 and have 18 entries. The second is that you
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have 17 entries and have a composite state. Under the hood, MSM adds a row for every
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event in the composite transition table. The third one is that you used a mpl::vector
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without the number of entries but are close to the MPL default of 50 and have a
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composite, thus pushing you above 50. Then you need mpl/vector60/70….hpp and a
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mpl/map60/70….hpp </p><p><span class="underline">Question</span>: Why do I get a very long compile error
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when I define more than 10 states in a state machine? </p><p><span class="underline">Answer</span>: Msm uses Boost.Fusion under the hood and
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this is the default maximum size. Please define the following macro before including any
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MSM headers: </p><p><code class="code">#define FUSION_MAX_VECTOR_SIZE 20 // or whatever you need </code></p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s05.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ar01s07.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"> Performance / Compilers </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Internals</td></tr></table></div></body></html> |