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POconst correctness problem with copy constructor?
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3825711
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3825735
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2010-09-29T20:46:37.393
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2010-09-29T20:57:48.477
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I am trying to wrap a C structure in a C++ class to take advantage of memory management and such. I have mad the structure a private member and provided a public function to provide access. The return type is constant, since all functions that take the object as an argument have <code>const</code> in their signature. <pre><code>#include <gsl/gsl_rng.h> class GSLRand { gsl_rng* r_; // see links below public: GSLRand() { gsl_rng_env_setup(); r_ = gsl_rng_alloc(gsl_rng_default); } ~GSLRand() { gsl_rng_free(r_); } const gsl_rng* rng() { return r_; } }; </code></pre> That all compiles nicely. The problem occurs when I get clever and try to add a copy constructor. Introducing it into the class like... <pre><code>public: .... GSLRand(const GSLRand& R) { r_ = gsl_rng_alloc(gsl_rng_taus); gsl_rng_memcpy(r_, R.rng()); } .... </code></pre> I get the following compiler error: <pre> GSLRand.h: In copy constructor ‘GSLRand::GSLRand(const GSLRand&)’: GSLRand.h:35: error: passing ‘const GSLRand’ as ‘this’ argument of ‘gsl_rng* GSLRand::rng()’ discards qualifiers </pre> I'm using g++ on a Mac. I have tried the different variants and still can't figure out how I'm confusing the compiler (or myself!). Interestingly, I get the identical error when I remove the <code>const</code> specifier from <code>rng()</code>. Any ideas? For documentation of the functions that are used: <a href="http://www.gnu.org/software/gsl/manual/html_node/Random-Number-Generation.html" rel="nofollow">random number generation</a>, the sections on "environment variables" and "copying generators."
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<c++><compiler-errors><gsl>
Title
const correctness problem with copy constructor?
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1. PO
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1. USJerry Gagelman
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2. PO
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